mercurial/keepalive.py

copies-rust: tokenize all paths into integer

Copy information for each changesets tend to affect a small new number of path.
However, each of these path might be handled a large number of time. Handling
HgPathBuf (aka `Vec<u8>`) is expensive. Handling integer is cheap.

With this patch we:
- turn any input path into an integer "token" early,
- do all the internal logic using such "token",
- turn "token" back into path right before returning a result.

This gives use a quite significant performance boost in our slower cases.

Repo            Case                                  Source-Rev   Dest-Rev      # of revisions  old time      new time      Difference    Factor    time per rev
---------------------------------------------------------------------------------------------------------------------------------------------------------------
pypy            x000_revs_x000_added_x_copies         8a3b5bfd266e 2c68e87c3efe :   6780 revs,   0.092828 s,   0.081225 s,  -0.011603 s, × 0.8750,    11 µs/rev
pypy            x0000_revs_x_added_0_copies           d1defd0dc478 c9cb1334cc78 :  43645 revs,   0.711975 s,   0.586011 s,  -0.125964 s, × 0.8231,    13 µs/rev
pypy            x0000_revs_xx000_added_x000_copies    08ea3258278e d9fa043f30c0 :  11316 revs,   0.124505 s,   0.114173 s,  -0.010332 s, × 0.9170,    10 µs/rev
netbeans        x000_revs_x000_added_x000_copies      ff453e9fee32 411350406ec2 :   5750 revs,   0.072072 s,   0.061004 s,  -0.011068 s, × 0.8464,    10 µs/rev
netbeans        x0000_revs_xx000_added_x000_copies    588c2d1ced70 1aad62e59ddd :  66949 revs,   0.682732 s,   0.535874 s,  -0.146858 s, × 0.7849,     8 µs/rev
mozilla-central x00000_revs_x0000_added_x0000_copies  6832ae71433c 4c222a1d9a00 : 153721 revs,   1.935918 s,   1.781383 s,  -0.154535 s, × 0.9202,    11 µs/rev
mozilla-central x00000_revs_x00000_added_x000_copies  76caed42cf7c 1daa622bbe42 : 204976 revs,   2.827320 s,   2.603867 s,  -0.223453 s, × 0.9210,    12 µs/rev
mozilla-try     x0000_revs_xx000_added_x000_copies    89294cd501d9 7ccb2fc7ccb5 :  97052 revs,   3.243010 s,   1.529120 s,  -1.713890 s, × 0.4715,    15 µs/rev
mozilla-try     x00000_revs_x_added_0_copies          6a320851d377 1ebb79acd503 : 363753 revs,   5.693818 s,   4.842699 s,  -0.851119 s, × 0.8505,    13 µs/rev
mozilla-try     x00000_revs_x_added_x_copies          5173c4b6f97c 95d83ee7242d : 362229 revs,   5.677655 s,   4.761732 s,  -0.915923 s, × 0.8387,    13 µs/rev
mozilla-try     x00000_revs_x000_added_x_copies       9126823d0e9c ca82787bb23c : 359344 revs,   5.563370 s,   4.733912 s,  -0.829458 s, × 0.8509,    13 µs/rev
mozilla-try     x00000_revs_x0000_added_x0000_copies  8d3fafa80d4b eb884023b810 : 192665 revs,   2.864099 s,   2.593410 s,  -0.270689 s, × 0.9055,    13 µs/rev
mozilla-try     x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d : 228985 revs, 113.297287 s,  41.041198 s, -72.256089 s, × 0.3622,   179 µs/rev
mozilla-try     x00000_revs_x00000_added_x000_copies  9b2a99adc05e 8e29777b48e6 : 382065 revs,  59.498652 s,  27.915689 s, -31.582963 s, × 0.4692,    73 µs/rev





Full timing comparison between this revision and the previous one:


Repo            Case                                  Source-Rev   Dest-Rev      # of revisions  old time      new time      Difference    Factor    time per rev
---------------------------------------------------------------------------------------------------------------------------------------------------------------
mercurial       x_revs_x_added_0_copies               ad6b123de1c7 39cfcef4f463 :      1 revs,   0.000042 s,   0.000042 s,  +0.000000 s, × 1.0000,    42 µs/rev
mercurial       x_revs_x_added_x_copies               2b1c78674230 0c1d10351869 :      6 revs,   0.000104 s,   0.000110 s,  +0.000006 s, × 1.0577,    18 µs/rev
mercurial       x000_revs_x000_added_x_copies         81f8ff2a9bf2 dd3267698d84 :   1032 revs,   0.004913 s,   0.004918 s,  +0.000005 s, × 1.0010,     4 µs/rev
pypy            x_revs_x_added_0_copies               aed021ee8ae8 099ed31b181b :      9 revs,   0.000191 s,   0.000195 s,  +0.000004 s, × 1.0209,    21 µs/rev
pypy            x_revs_x000_added_0_copies            4aa4e1f8e19a 359343b9ac0e :      1 revs,   0.000050 s,   0.000049 s,  -0.000001 s, × 0.9800,    49 µs/rev
pypy            x_revs_x_added_x_copies               ac52eb7bbbb0 72e022663155 :      7 revs,   0.000112 s,   0.000112 s,  +0.000000 s, × 1.0000,    16 µs/rev
pypy            x_revs_x00_added_x_copies             c3b14617fbd7 ace7255d9a26 :      1 revs,   0.000288 s,   0.000324 s,  +0.000036 s, × 1.1250,   324 µs/rev
pypy            x_revs_x000_added_x000_copies         df6f7a526b60 a83dc6a2d56f :      6 revs,   0.010411 s,   0.010611 s,  +0.000200 s, × 1.0192,  1768 µs/rev
pypy            x000_revs_xx00_added_0_copies         89a76aede314 2f22446ff07e :   4785 revs,   0.052852 s,   0.050835 s,  -0.002017 s, × 0.9618,    10 µs/rev
pypy            x000_revs_x000_added_x_copies         8a3b5bfd266e 2c68e87c3efe :   6780 revs,   0.092828 s,   0.081225 s,  -0.011603 s, × 0.8750,    11 µs/rev
pypy            x000_revs_x000_added_x000_copies      89a76aede314 7b3dda341c84 :   5441 revs,   0.063269 s,   0.061291 s,  -0.001978 s, × 0.9687,    11 µs/rev
pypy            x0000_revs_x_added_0_copies           d1defd0dc478 c9cb1334cc78 :  43645 revs,   0.711975 s,   0.586011 s,  -0.125964 s, × 0.8231,    13 µs/rev
pypy            x0000_revs_xx000_added_0_copies       bf2c629d0071 4ffed77c095c :      2 revs,   0.012771 s,   0.012824 s,  +0.000053 s, × 1.0042,  6412 µs/rev
pypy            x0000_revs_xx000_added_x000_copies    08ea3258278e d9fa043f30c0 :  11316 revs,   0.124505 s,   0.114173 s,  -0.010332 s, × 0.9170,    10 µs/rev
netbeans        x_revs_x_added_0_copies               fb0955ffcbcd a01e9239f9e7 :      2 revs,   0.000082 s,   0.000085 s,  +0.000003 s, × 1.0366,    42 µs/rev
netbeans        x_revs_x000_added_0_copies            6f360122949f 20eb231cc7d0 :      2 revs,   0.000111 s,   0.000108 s,  -0.000003 s, × 0.9730,    54 µs/rev
netbeans        x_revs_x_added_x_copies               1ada3faf6fb6 5a39d12eecf4 :      3 revs,   0.000171 s,   0.000175 s,  +0.000004 s, × 1.0234,    58 µs/rev
netbeans        x_revs_x00_added_x_copies             35be93ba1e2c 9eec5e90c05f :      9 revs,   0.000708 s,   0.000719 s,  +0.000011 s, × 1.0155,    79 µs/rev
netbeans        x000_revs_xx00_added_0_copies         eac3045b4fdd 51d4ae7f1290 :   1421 revs,   0.010608 s,   0.010175 s,  -0.000433 s, × 0.9592,     7 µs/rev
netbeans        x000_revs_x000_added_x_copies         e2063d266acd 6081d72689dc :   1533 revs,   0.015635 s,   0.015569 s,  -0.000066 s, × 0.9958,    10 µs/rev
netbeans        x000_revs_x000_added_x000_copies      ff453e9fee32 411350406ec2 :   5750 revs,   0.072072 s,   0.061004 s,  -0.011068 s, × 0.8464,    10 µs/rev
netbeans        x0000_revs_xx000_added_x000_copies    588c2d1ced70 1aad62e59ddd :  66949 revs,   0.682732 s,   0.535874 s,  -0.146858 s, × 0.7849,     8 µs/rev
mozilla-central x_revs_x_added_0_copies               3697f962bb7b 7015fcdd43a2 :      2 revs,   0.000090 s,   0.000090 s,  +0.000000 s, × 1.0000,    45 µs/rev
mozilla-central x_revs_x000_added_0_copies            dd390860c6c9 40d0c5bed75d :      8 revs,   0.000210 s,   0.000281 s,  +0.000071 s, × 1.3381,    35 µs/rev
mozilla-central x_revs_x_added_x_copies               8d198483ae3b 14207ffc2b2f :      9 revs,   0.000182 s,   0.000187 s,  +0.000005 s, × 1.0275,    20 µs/rev
mozilla-central x_revs_x00_added_x_copies             98cbc58cc6bc 446a150332c3 :      7 revs,   0.000594 s,   0.000660 s,  +0.000066 s, × 1.1111,    94 µs/rev
mozilla-central x_revs_x000_added_x000_copies         3c684b4b8f68 0a5e72d1b479 :      3 revs,   0.003102 s,   0.003385 s,  +0.000283 s, × 1.0912,  1128 µs/rev
mozilla-central x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :      6 revs,   0.060234 s,   0.069812 s,  +0.009578 s, × 1.1590, 11635 µs/rev
mozilla-central x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :   1593 revs,   0.006300 s,   0.006503 s,  +0.000203 s, × 1.0322,     4 µs/rev
mozilla-central x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :     41 revs,   0.004817 s,   0.004988 s,  +0.000171 s, × 1.0355,   121 µs/rev
mozilla-central x000_revs_x000_added_x000_copies      7c97034feb78 4407bd0c6330 :   7839 revs,   0.065451 s,   0.063963 s,  -0.001488 s, × 0.9773,     8 µs/rev
mozilla-central x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :    615 revs,   0.026282 s,   0.026225 s,  -0.000057 s, × 0.9978,    42 µs/rev
mozilla-central x0000_revs_xx000_added_x000_copies    f78c615a656c 96a38b690156 :  30263 revs,   0.206873 s,   0.201377 s,  -0.005496 s, × 0.9734,     6 µs/rev
mozilla-central x00000_revs_x0000_added_x0000_copies  6832ae71433c 4c222a1d9a00 : 153721 revs,   1.935918 s,   1.781383 s,  -0.154535 s, × 0.9202,    11 µs/rev
mozilla-central x00000_revs_x00000_added_x000_copies  76caed42cf7c 1daa622bbe42 : 204976 revs,   2.827320 s,   2.603867 s,  -0.223453 s, × 0.9210,    12 µs/rev
mozilla-try     x_revs_x_added_0_copies               aaf6dde0deb8 9790f499805a :      2 revs,   0.000842 s,   0.000845 s,  +0.000003 s, × 1.0036,   422 µs/rev
mozilla-try     x_revs_x000_added_0_copies            d8d0222927b4 5bb8ce8c7450 :      2 revs,   0.000870 s,   0.000862 s,  -0.000008 s, × 0.9908,   431 µs/rev
mozilla-try     x_revs_x_added_x_copies               092fcca11bdb 936255a0384a :      4 revs,   0.000165 s,   0.000161 s,  -0.000004 s, × 0.9758,    40 µs/rev
mozilla-try     x_revs_x00_added_x_copies             b53d2fadbdb5 017afae788ec :      2 revs,   0.001145 s,   0.001163 s,  +0.000018 s, × 1.0157,   581 µs/rev
mozilla-try     x_revs_x000_added_x000_copies         20408ad61ce5 6f0ee96e21ad :      1 revs,   0.026500 s,   0.032414 s,  +0.005914 s, × 1.2232, 32414 µs/rev
mozilla-try     x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :      6 revs,   0.059407 s,   0.070149 s,  +0.010742 s, × 1.1808, 11691 µs/rev
mozilla-try     x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :   1593 revs,   0.006325 s,   0.006526 s,  +0.000201 s, × 1.0318,     4 µs/rev
mozilla-try     x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :     41 revs,   0.005171 s,   0.005187 s,  +0.000016 s, × 1.0031,   126 µs/rev
mozilla-try     x000_revs_x000_added_x000_copies      1346fd0130e4 4c65cbdabc1f :   6657 revs,   0.066837 s,   0.065047 s,  -0.001790 s, × 0.9732,     9 µs/rev
mozilla-try     x0000_revs_x_added_0_copies           63519bfd42ee a36a2a865d92 :  40314 revs,   0.314252 s,   0.301129 s,  -0.013123 s, × 0.9582,     7 µs/rev
mozilla-try     x0000_revs_x_added_x_copies           9fe69ff0762d bcabf2a78927 :  38690 revs,   0.304160 s,   0.280683 s,  -0.023477 s, × 0.9228,     7 µs/rev
mozilla-try     x0000_revs_xx000_added_x_copies       156f6e2674f2 4d0f2c178e66 :   8598 revs,   0.089223 s,   0.084897 s,  -0.004326 s, × 0.9515,     9 µs/rev
mozilla-try     x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :    615 revs,   0.026711 s,   0.026620 s,  -0.000091 s, × 0.9966,    43 µs/rev
mozilla-try     x0000_revs_xx000_added_x000_copies    89294cd501d9 7ccb2fc7ccb5 :  97052 revs,   3.243010 s,   1.529120 s,  -1.713890 s, × 0.4715,    15 µs/rev
mozilla-try     x0000_revs_x0000_added_x0000_copies   e928c65095ed e951f4ad123a :  52031 revs,   0.756500 s,   0.738709 s,  -0.017791 s, × 0.9765,    14 µs/rev
mozilla-try     x00000_revs_x_added_0_copies          6a320851d377 1ebb79acd503 : 363753 revs,   5.693818 s,   4.842699 s,  -0.851119 s, × 0.8505,    13 µs/rev
mozilla-try     x00000_revs_x00000_added_0_copies     dc8a3ca7010e d16fde900c9c :  34414 revs,   0.590904 s,   0.596946 s,  +0.006042 s, × 1.0102,    17 µs/rev
mozilla-try     x00000_revs_x_added_x_copies          5173c4b6f97c 95d83ee7242d : 362229 revs,   5.677655 s,   4.761732 s,  -0.915923 s, × 0.8387,    13 µs/rev
mozilla-try     x00000_revs_x000_added_x_copies       9126823d0e9c ca82787bb23c : 359344 revs,   5.563370 s,   4.733912 s,  -0.829458 s, × 0.8509,    13 µs/rev
mozilla-try     x00000_revs_x0000_added_x0000_copies  8d3fafa80d4b eb884023b810 : 192665 revs,   2.864099 s,   2.593410 s,  -0.270689 s, × 0.9055,    13 µs/rev
mozilla-try     x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d : 228985 revs, 113.297287 s,  41.041198 s, -72.256089 s, × 0.3622,   179 µs/rev
mozilla-try     x00000_revs_x00000_added_x000_copies  9b2a99adc05e 8e29777b48e6 : 382065 revs,  59.498652 s,  27.915689 s, -31.582963 s, × 0.4692,    73 µs/rev


Full timing comparison between this revision and the filelog copy tracing.

Repo            Case                                  Source-Rev   Dest-Rev      # of revisions   filelog      sidedata      Difference    Factor    time per rev
---------------------------------------------------------------------------------------------------------------------------------------------------------------
mercurial       x_revs_x_added_0_copies               ad6b123de1c7 39cfcef4f463 :       1 revs,   0.000903 s,  0.000042 s,  -0.000861 s, × 0.0465,    41 µs/rev
mercurial       x_revs_x_added_x_copies               2b1c78674230 0c1d10351869 :       6 revs,   0.001861 s,  0.000110 s,  -0.001751 s, × 0.0591,    18 µs/rev
mercurial       x000_revs_x000_added_x_copies         81f8ff2a9bf2 dd3267698d84 :    1032 revs,   0.018577 s,  0.004918 s,  -0.013659 s, × 0.2647,     4 µs/rev
pypy            x_revs_x_added_0_copies               aed021ee8ae8 099ed31b181b :       9 revs,   0.001519 s,  0.000195 s,  -0.001324 s, × 0.1283,    21 µs/rev
pypy            x_revs_x000_added_0_copies            4aa4e1f8e19a 359343b9ac0e :       1 revs,   0.213855 s,  0.000049 s,  -0.350d73 s, × 0.0002,    48 µs/rev
pypy            x_revs_x_added_x_copies               ac52eb7bbbb0 72e022663155 :       7 revs,   0.017022 s,  0.000112 s,  -0.016910 s, × 0.0065,    15 µs/rev
pypy            x_revs_x00_added_x_copies             c3b14617fbd7 ace7255d9a26 :       1 revs,   0.019398 s,  0.000324 s,  -0.019074 s, × 0.0167,   323 µs/rev
pypy            x_revs_x000_added_x000_copies         df6f7a526b60 a83dc6a2d56f :       6 revs,   0.769467 s,  0.010611 s,  -0.758856 s, × 0.0137,  1768 µs/rev
pypy            x000_revs_xx00_added_0_copies         89a76aede314 2f22446ff07e :    4785 revs,   1.221952 s,  0.050835 s,  -1.171117 s, × 0.0416,    10 µs/rev
pypy            x000_revs_x000_added_x_copies         8a3b5bfd266e 2c68e87c3efe :    6780 revs,   1.304007 s,  0.081225 s,  -1.222782 s, × 0.0622,    11 µs/rev
pypy            x000_revs_x000_added_x000_copies      89a76aede314 7b3dda341c84 :    5441 revs,   1.686610 s,  0.061291 s,  -1.625319 s, × 0.0363,    11 µs/rev
pypy            x0000_revs_x_added_0_copies           d1defd0dc478 c9cb1334cc78 :   43645 revs,   0.001107 s,  0.586011 s,  +0.584904 s, × 529.36,    13 µs/rev
pypy            x0000_revs_xx000_added_0_copies       bf2c629d0071 4ffed77c095c :       2 revs,   1.100760 s,  0.012824 s,  -1.087936 s, × 0.0116,  6408 µs/rev
pypy            x0000_revs_xx000_added_x000_copies    08ea3258278e d9fa043f30c0 :   11316 revs,   1.350547 s,  0.114173 s,  -1.236374 s, × 0.0845,    10 µs/rev
netbeans        x_revs_x_added_0_copies               fb0955ffcbcd a01e9239f9e7 :       2 revs,   0.027864 s,  0.000085 s,  -0.027779 s, × 0.0030,    42 µs/rev
netbeans        x_revs_x000_added_0_copies            6f360122949f 20eb231cc7d0 :       2 revs,   0.132479 s,  0.000108 s,  -0.132371 s, × 0.0008,    53 µs/rev
netbeans        x_revs_x_added_x_copies               1ada3faf6fb6 5a39d12eecf4 :       3 revs,   0.025405 s,  0.000175 s,  -0.025230 s, × 0.0068,    58 µs/rev
netbeans        x_revs_x00_added_x_copies             35be93ba1e2c 9eec5e90c05f :       9 revs,   0.053244 s,  0.000719 s,  -0.052525 s, × 0.0135,    79 µs/rev
netbeans        x000_revs_xx00_added_0_copies         eac3045b4fdd 51d4ae7f1290 :    1421 revs,   0.038017 s,  0.010175 s,  -0.027842 s, × 0.2676,     7 µs/rev
netbeans        x000_revs_x000_added_x_copies         e2063d266acd 6081d72689dc :    1533 revs,   0.198308 s,  0.015569 s,  -0.182739 s, × 0.0785,    10 µs/rev
netbeans        x000_revs_x000_added_x000_copies      ff453e9fee32 411350406ec2 :    5750 revs,   0.949749 s,  0.061004 s,  -0.888745 s, × 0.0642,    10 µs/rev
netbeans        x0000_revs_xx000_added_x000_copies    588c2d1ced70 1aad62e59ddd :   66949 revs,   3.932262 s,  0.535874 s,  -3.396388 s, × 0.1362,     8 µs/rev
mozilla-central x_revs_x_added_0_copies               3697f962bb7b 7015fcdd43a2 :       2 revs,   0.024490 s,  0.000090 s,  -0.024400 s, × 0.0036,    44 µs/rev
mozilla-central x_revs_x000_added_0_copies            dd390860c6c9 40d0c5bed75d :       8 revs,   0.143885 s,  0.000281 s,  -0.143604 s, × 0.0019,    35 µs/rev
mozilla-central x_revs_x_added_x_copies               8d198483ae3b 14207ffc2b2f :       9 revs,   0.025471 s,  0.000187 s,  -0.025284 s, × 0.0073,    20 µs/rev
mozilla-central x_revs_x00_added_x_copies             98cbc58cc6bc 446a150332c3 :       7 revs,   0.086013 s,  0.000660 s,  -0.085353 s, × 0.0076,    94 µs/rev
mozilla-central x_revs_x000_added_x000_copies         3c684b4b8f68 0a5e72d1b479 :       3 revs,   0.200726 s,  0.003385 s,  -0.197341 s, × 0.0168,  1127 µs/rev
mozilla-central x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :       6 revs,   2.224171 s,  0.069812 s,  -2.154359 s, × 0.0313, 11633 µs/rev
mozilla-central x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :    1593 revs,   0.090780 s,  0.006503 s,  -0.084277 s, × 0.0716,     4 µs/rev
mozilla-central x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :      41 revs,   0.764805 s,  0.004988 s,  -0.759817 s, × 0.0065,   121 µs/rev
mozilla-central x000_revs_x000_added_x000_copies      7c97034feb78 4407bd0c6330 :    7839 revs,   1.161405 s,  0.063963 s,  -1.097442 s, × 0.0550,     8 µs/rev
mozilla-central x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :     615 revs,   6.816186 s,  0.026225 s,  -6.789961 s, × 0.0038,    42 µs/rev
mozilla-central x0000_revs_xx000_added_x000_copies    f78c615a656c 96a38b690156 :   30263 revs,   3.374819 s,  0.201377 s,  -3.173442 s, × 0.0596,     6 µs/rev
mozilla-central x00000_revs_x0000_added_x0000_copies  6832ae71433c 4c222a1d9a00 :  153721 revs,  16.285469 s,  1.781383 s, -14.504086 s, × 0.1093,    11 µs/rev
mozilla-central x00000_revs_x00000_added_x000_copies  76caed42cf7c 1daa622bbe42 :  204976 revs,  21.207733 s,  2.603867 s, -18.603866 s, × 0.1227,    12 µs/rev
mozilla-try     x_revs_x_added_0_copies               aaf6dde0deb8 9790f499805a :       2 revs,   0.080843 s,  0.000845 s,  -0.079998 s, × 0.0104,   422 µs/rev
mozilla-try     x_revs_x000_added_0_copies            d8d0222927b4 5bb8ce8c7450 :       2 revs,   0.511068 s,  0.000862 s,  -0.510206 s, × 0.0016,   430 µs/rev
mozilla-try     x_revs_x_added_x_copies               092fcca11bdb 936255a0384a :       4 revs,   0.021573 s,  0.000161 s,  -0.021412 s, × 0.0074,    40 µs/rev
mozilla-try     x_revs_x00_added_x_copies             b53d2fadbdb5 017afae788ec :       2 revs,   0.227726 s,  0.001163 s,  -0.226563 s, × 0.0051,   581 µs/rev
mozilla-try     x_revs_x000_added_x000_copies         20408ad61ce5 6f0ee96e21ad :       1 revs,   1.120448 s,  0.032414 s,  -1.088034 s, × 0.0289, 32381 µs/rev
mozilla-try     x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :       6 revs,   2.241713 s,  0.070149 s,  -2.171564 s, × 0.0312, 11689 µs/rev
mozilla-try     x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :    1593 revs,   0.090633 s,  0.006526 s,  -0.084107 s, × 0.0720,     4 µs/rev
mozilla-try     x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :      41 revs,   0.770403 s,  0.005187 s,  -0.765216 s, × 0.0067,   126 µs/rev
mozilla-try     x000_revs_x000_added_x000_copies      1346fd0130e4 4c65cbdabc1f :    6657 revs,   1.184557 s,  0.065047 s,  -1.119510 s, × 0.0549,     9 µs/rev
mozilla-try     x0000_revs_x_added_0_copies           63519bfd42ee a36a2a865d92 :   40314 revs,   0.085790 s,  0.301129 s,  +0.215339 s, × 3.5100,     7 µs/rev
mozilla-try     x0000_revs_x_added_x_copies           9fe69ff0762d bcabf2a78927 :   38690 revs,   0.080616 s,  0.280683 s,  +0.200067 s, × 3.4817,     7 µs/rev
mozilla-try     x0000_revs_xx000_added_x_copies       156f6e2674f2 4d0f2c178e66 :    8598 revs,   7.712554 s,  0.084897 s,  -7.627657 s, × 0.0110,     9 µs/rev
mozilla-try     x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :     615 revs,   6.937294 s,  0.026620 s,  -6.910674 s, × 0.0038,    43 µs/rev
mozilla-try     x0000_revs_xx000_added_x000_copies    89294cd501d9 7ccb2fc7ccb5 :   97052 revs,   7.712313 s,  1.529120 s,  -6.183193 s, × 0.1982,    15 µs/rev
mozilla-try     x0000_revs_x0000_added_x0000_copies   e928c65095ed e951f4ad123a :   52031 revs,   9.966910 s,  0.738709 s,  -9.228201 s, × 0.0741,    14 µs/rev
mozilla-try     x00000_revs_x_added_0_copies          6a320851d377 1ebb79acd503 :  363753 revs,   0.090397 s,  4.842699 s,  +4.752302 s, × 53.571,    13 µs/rev
mozilla-try     x00000_revs_x00000_added_0_copies     dc8a3ca7010e d16fde900c9c :   34414 revs,  27.817167 s,  0.596946 s, -27.220221 s, × 0.0214,    17 µs/rev
mozilla-try     x00000_revs_x_added_x_copies          5173c4b6f97c 95d83ee7242d :  362229 revs,   0.091305 s,  4.761732 s,  +4.670427 s, × 52.151,    13 µs/rev
mozilla-try     x00000_revs_x000_added_x_copies       9126823d0e9c ca82787bb23c :  359344 revs,   0.231183 s,  4.733912 s,  +4.502729 s, × 20.476,    13 µs/rev
mozilla-try     x00000_revs_x0000_added_x0000_copies  8d3fafa80d4b eb884023b810 :  192665 revs,  19.830617 s,  2.593410 s, -17.237207 s, × 0.1307,    13 µs/rev
mozilla-try     x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d :  228985 revs,  21.743873 s, 41.041198 s, +19.297325 s, × 1.8874,   179 µs/rev
mozilla-try     x00000_revs_x00000_added_x000_copies  9b2a99adc05e 8e29777b48e6 :  382065 revs,  25.935037 s, 27.915689 s,  +1.980652 s, × 1.0763,    73 µs/rev

Differential Revision: https://phab.mercurial-scm.org/D9493

#   This library is free software; you can redistribute it and/or
#   modify it under the terms of the GNU Lesser General Public
#   License as published by the Free Software Foundation; either
#   version 2.1 of the License, or (at your option) any later version.
#
#   This library is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
#   Lesser General Public License for more details.
#
#   You should have received a copy of the GNU Lesser General Public
#   License along with this library; if not, see
#   <http://www.gnu.org/licenses/>.

# This file is part of urlgrabber, a high-level cross-protocol url-grabber
# Copyright 2002-2004 Michael D. Stenner, Ryan Tomayko

# Modified by Benoit Boissinot:
#  - fix for digest auth (inspired from urllib2.py @ Python v2.4)
# Modified by Dirkjan Ochtman:
#  - import md5 function from a local util module
# Modified by Augie Fackler:
#  - add safesend method and use it to prevent broken pipe errors
#    on large POST requests

"""An HTTP handler for urllib2 that supports HTTP 1.1 and keepalive.

>>> import urllib2
>>> from keepalive import HTTPHandler
>>> keepalive_handler = HTTPHandler()
>>> opener = urlreq.buildopener(keepalive_handler)
>>> urlreq.installopener(opener)
>>>
>>> fo = urlreq.urlopen('http://www.python.org')

If a connection to a given host is requested, and all of the existing
connections are still in use, another connection will be opened.  If
the handler tries to use an existing connection but it fails in some
way, it will be closed and removed from the pool.

To remove the handler, simply re-run build_opener with no arguments, and
install that opener.

You can explicitly close connections by using the close_connection()
method of the returned file-like object (described below) or you can
use the handler methods:

  close_connection(host)
  close_all()
  open_connections()

NOTE: using the close_connection and close_all methods of the handler
should be done with care when using multiple threads.
  * there is nothing that prevents another thread from creating new
    connections immediately after connections are closed
  * no checks are done to prevent in-use connections from being closed

>>> keepalive_handler.close_all()

EXTRA ATTRIBUTES AND METHODS

  Upon a status of 200, the object returned has a few additional
  attributes and methods, which should not be used if you want to
  remain consistent with the normal urllib2-returned objects:

    close_connection()  -  close the connection to the host
    readlines()         -  you know, readlines()
    status              -  the return status (i.e. 404)
    reason              -  english translation of status (i.e. 'File not found')

  If you want the best of both worlds, use this inside an
  AttributeError-catching try:

  >>> try: status = fo.status
  >>> except AttributeError: status = None

  Unfortunately, these are ONLY there if status == 200, so it's not
  easy to distinguish between non-200 responses.  The reason is that
  urllib2 tries to do clever things with error codes 301, 302, 401,
  and 407, and it wraps the object upon return.
"""

# $Id: keepalive.py,v 1.14 2006/04/04 21:00:32 mstenner Exp $

from __future__ import absolute_import, print_function

import collections
import errno
import hashlib
import socket
import sys
import threading

from .i18n import _
from .pycompat import getattr
from .node import hex
from . import (
    pycompat,
    urllibcompat,
    util,
)
from .utils import procutil

httplib = util.httplib
urlerr = util.urlerr
urlreq = util.urlreq

DEBUG = None


class ConnectionManager(object):
    """
    The connection manager must be able to:
      * keep track of all existing
    """

    def __init__(self):
        self._lock = threading.Lock()
        self._hostmap = collections.defaultdict(list)  # host -> [connection]
        self._connmap = {}  # map connections to host
        self._readymap = {}  # map connection to ready state

    def add(self, host, connection, ready):
        self._lock.acquire()
        try:
            self._hostmap[host].append(connection)
            self._connmap[connection] = host
            self._readymap[connection] = ready
        finally:
            self._lock.release()

    def remove(self, connection):
        self._lock.acquire()
        try:
            try:
                host = self._connmap[connection]
            except KeyError:
                pass
            else:
                del self._connmap[connection]
                del self._readymap[connection]
                self._hostmap[host].remove(connection)
                if not self._hostmap[host]:
                    del self._hostmap[host]
        finally:
            self._lock.release()

    def set_ready(self, connection, ready):
        try:
            self._readymap[connection] = ready
        except KeyError:
            pass

    def get_ready_conn(self, host):
        conn = None
        self._lock.acquire()
        try:
            for c in self._hostmap[host]:
                if self._readymap[c]:
                    self._readymap[c] = False
                    conn = c
                    break
        finally:
            self._lock.release()
        return conn

    def get_all(self, host=None):
        if host:
            return list(self._hostmap[host])
        else:
            return dict(self._hostmap)


class KeepAliveHandler(object):
    def __init__(self, timeout=None):
        self._cm = ConnectionManager()
        self._timeout = timeout
        self.requestscount = 0
        self.sentbytescount = 0

    #### Connection Management
    def open_connections(self):
        """return a list of connected hosts and the number of connections
        to each.  [('foo.com:80', 2), ('bar.org', 1)]"""
        return [(host, len(li)) for (host, li) in self._cm.get_all().items()]

    def close_connection(self, host):
        """close connection(s) to <host>
        host is the host:port spec, as in 'www.cnn.com:8080' as passed in.
        no error occurs if there is no connection to that host."""
        for h in self._cm.get_all(host):
            self._cm.remove(h)
            h.close()

    def close_all(self):
        """close all open connections"""
        for host, conns in pycompat.iteritems(self._cm.get_all()):
            for h in conns:
                self._cm.remove(h)
                h.close()

    def _request_closed(self, request, host, connection):
        """tells us that this request is now closed and that the
        connection is ready for another request"""
        self._cm.set_ready(connection, True)

    def _remove_connection(self, host, connection, close=0):
        if close:
            connection.close()
        self._cm.remove(connection)

    #### Transaction Execution
    def http_open(self, req):
        return self.do_open(HTTPConnection, req)

    def do_open(self, http_class, req):
        host = urllibcompat.gethost(req)
        if not host:
            raise urlerr.urlerror(b'no host given')

        try:
            h = self._cm.get_ready_conn(host)
            while h:
                r = self._reuse_connection(h, req, host)

                # if this response is non-None, then it worked and we're
                # done.  Break out, skipping the else block.
                if r:
                    break

                # connection is bad - possibly closed by server
                # discard it and ask for the next free connection
                h.close()
                self._cm.remove(h)
                h = self._cm.get_ready_conn(host)
            else:
                # no (working) free connections were found.  Create a new one.
                h = http_class(host, timeout=self._timeout)
                if DEBUG:
                    DEBUG.info(
                        b"creating new connection to %s (%d)", host, id(h)
                    )
                self._cm.add(host, h, False)
                self._start_transaction(h, req)
                r = h.getresponse()
        # The string form of BadStatusLine is the status line. Add some context
        # to make the error message slightly more useful.
        except httplib.BadStatusLine as err:
            raise urlerr.urlerror(
                _(b'bad HTTP status line: %s') % pycompat.sysbytes(err.line)
            )
        except (socket.error, httplib.HTTPException) as err:
            raise urlerr.urlerror(err)

        # If not a persistent connection, don't try to reuse it. Look
        # for this using getattr() since vcr doesn't define this
        # attribute, and in that case always close the connection.
        if getattr(r, 'will_close', True):
            self._cm.remove(h)

        if DEBUG:
            DEBUG.info(b"STATUS: %s, %s", r.status, r.reason)
        r._handler = self
        r._host = host
        r._url = req.get_full_url()
        r._connection = h
        r.code = r.status
        r.headers = r.msg
        r.msg = r.reason

        return r

    def _reuse_connection(self, h, req, host):
        """start the transaction with a re-used connection
        return a response object (r) upon success or None on failure.
        This DOES not close or remove bad connections in cases where
        it returns.  However, if an unexpected exception occurs, it
        will close and remove the connection before re-raising.
        """
        try:
            self._start_transaction(h, req)
            r = h.getresponse()
            # note: just because we got something back doesn't mean it
            # worked.  We'll check the version below, too.
        except (socket.error, httplib.HTTPException):
            r = None
        except:  # re-raises
            # adding this block just in case we've missed
            # something we will still raise the exception, but
            # lets try and close the connection and remove it
            # first.  We previously got into a nasty loop
            # where an exception was uncaught, and so the
            # connection stayed open.  On the next try, the
            # same exception was raised, etc.  The trade-off is
            # that it's now possible this call will raise
            # a DIFFERENT exception
            if DEBUG:
                DEBUG.error(
                    b"unexpected exception - closing connection to %s (%d)",
                    host,
                    id(h),
                )
            self._cm.remove(h)
            h.close()
            raise

        if r is None or r.version == 9:
            # httplib falls back to assuming HTTP 0.9 if it gets a
            # bad header back.  This is most likely to happen if
            # the socket has been closed by the server since we
            # last used the connection.
            if DEBUG:
                DEBUG.info(
                    b"failed to re-use connection to %s (%d)", host, id(h)
                )
            r = None
        else:
            if DEBUG:
                DEBUG.info(b"re-using connection to %s (%d)", host, id(h))

        return r

    def _start_transaction(self, h, req):
        oldbytescount = getattr(h, 'sentbytescount', 0)

        # What follows mostly reimplements HTTPConnection.request()
        # except it adds self.parent.addheaders in the mix and sends headers
        # in a deterministic order (to make testing easier).
        headers = util.sortdict(self.parent.addheaders)
        headers.update(sorted(req.headers.items()))
        headers.update(sorted(req.unredirected_hdrs.items()))
        headers = util.sortdict((n.lower(), v) for n, v in headers.items())
        skipheaders = {}
        for n in ('host', 'accept-encoding'):
            if n in headers:
                skipheaders['skip_' + n.replace('-', '_')] = 1
        try:
            if urllibcompat.hasdata(req):
                data = urllibcompat.getdata(req)
                h.putrequest(
                    req.get_method(),
                    urllibcompat.getselector(req),
                    **skipheaders
                )
                if 'content-type' not in headers:
                    h.putheader(
                        'Content-type', 'application/x-www-form-urlencoded'
                    )
                if 'content-length' not in headers:
                    h.putheader('Content-length', '%d' % len(data))
            else:
                h.putrequest(
                    req.get_method(),
                    urllibcompat.getselector(req),
                    **skipheaders
                )
        except socket.error as err:
            raise urlerr.urlerror(err)
        for k, v in headers.items():
            h.putheader(k, v)
        h.endheaders()
        if urllibcompat.hasdata(req):
            h.send(data)

        # This will fail to record events in case of I/O failure. That's OK.
        self.requestscount += 1
        self.sentbytescount += getattr(h, 'sentbytescount', 0) - oldbytescount

        try:
            self.parent.requestscount += 1
            self.parent.sentbytescount += (
                getattr(h, 'sentbytescount', 0) - oldbytescount
            )
        except AttributeError:
            pass


class HTTPHandler(KeepAliveHandler, urlreq.httphandler):
    pass


class HTTPResponse(httplib.HTTPResponse):
    # we need to subclass HTTPResponse in order to
    # 1) add readline(), readlines(), and readinto() methods
    # 2) add close_connection() methods
    # 3) add info() and geturl() methods

    # in order to add readline(), read must be modified to deal with a
    # buffer.  example: readline must read a buffer and then spit back
    # one line at a time.  The only real alternative is to read one
    # BYTE at a time (ick).  Once something has been read, it can't be
    # put back (ok, maybe it can, but that's even uglier than this),
    # so if you THEN do a normal read, you must first take stuff from
    # the buffer.

    # the read method wraps the original to accommodate buffering,
    # although read() never adds to the buffer.
    # Both readline and readlines have been stolen with almost no
    # modification from socket.py

    def __init__(self, sock, debuglevel=0, strict=0, method=None):
        extrakw = {}
        if not pycompat.ispy3:
            extrakw['strict'] = True
            extrakw['buffering'] = True
        httplib.HTTPResponse.__init__(
            self, sock, debuglevel=debuglevel, method=method, **extrakw
        )
        self.fileno = sock.fileno
        self.code = None
        self.receivedbytescount = 0
        self._rbuf = b''
        self._rbufsize = 8096
        self._handler = None  # inserted by the handler later
        self._host = None  # (same)
        self._url = None  # (same)
        self._connection = None  # (same)

    _raw_read = httplib.HTTPResponse.read
    _raw_readinto = getattr(httplib.HTTPResponse, 'readinto', None)

    # Python 2.7 has a single close() which closes the socket handle.
    # This method was effectively renamed to _close_conn() in Python 3. But
    # there is also a close(). _close_conn() is called by methods like
    # read().

    def close(self):
        if self.fp:
            self.fp.close()
            self.fp = None
            if self._handler:
                self._handler._request_closed(
                    self, self._host, self._connection
                )

    def _close_conn(self):
        self.close()

    def close_connection(self):
        self._handler._remove_connection(self._host, self._connection, close=1)
        self.close()

    def info(self):
        return self.headers

    def geturl(self):
        return self._url

    def read(self, amt=None):
        # the _rbuf test is only in this first if for speed.  It's not
        # logically necessary
        if self._rbuf and amt is not None:
            L = len(self._rbuf)
            if amt > L:
                amt -= L
            else:
                s = self._rbuf[:amt]
                self._rbuf = self._rbuf[amt:]
                return s
        # Careful! http.client.HTTPResponse.read() on Python 3 is
        # implemented using readinto(), which can duplicate self._rbuf
        # if it's not empty.
        s = self._rbuf
        self._rbuf = b''
        data = self._raw_read(amt)

        self.receivedbytescount += len(data)
        try:
            self._connection.receivedbytescount += len(data)
        except AttributeError:
            pass
        try:
            self._handler.parent.receivedbytescount += len(data)
        except AttributeError:
            pass

        s += data
        return s

    # stolen from Python SVN #68532 to fix issue1088
    def _read_chunked(self, amt):
        chunk_left = self.chunk_left
        parts = []

        while True:
            if chunk_left is None:
                line = self.fp.readline()
                i = line.find(b';')
                if i >= 0:
                    line = line[:i]  # strip chunk-extensions
                try:
                    chunk_left = int(line, 16)
                except ValueError:
                    # close the connection as protocol synchronization is
                    # probably lost
                    self.close()
                    raise httplib.IncompleteRead(b''.join(parts))
                if chunk_left == 0:
                    break
            if amt is None:
                parts.append(self._safe_read(chunk_left))
            elif amt < chunk_left:
                parts.append(self._safe_read(amt))
                self.chunk_left = chunk_left - amt
                return b''.join(parts)
            elif amt == chunk_left:
                parts.append(self._safe_read(amt))
                self._safe_read(2)  # toss the CRLF at the end of the chunk
                self.chunk_left = None
                return b''.join(parts)
            else:
                parts.append(self._safe_read(chunk_left))
                amt -= chunk_left

            # we read the whole chunk, get another
            self._safe_read(2)  # toss the CRLF at the end of the chunk
            chunk_left = None

        # read and discard trailer up to the CRLF terminator
        ### note: we shouldn't have any trailers!
        while True:
            line = self.fp.readline()
            if not line:
                # a vanishingly small number of sites EOF without
                # sending the trailer
                break
            if line == b'\r\n':
                break

        # we read everything; close the "file"
        self.close()

        return b''.join(parts)

    def readline(self):
        # Fast path for a line is already available in read buffer.
        i = self._rbuf.find(b'\n')
        if i >= 0:
            i += 1
            line = self._rbuf[:i]
            self._rbuf = self._rbuf[i:]
            return line

        # No newline in local buffer. Read until we find one.
        # readinto read via readinto will already return _rbuf
        if self._raw_readinto is None:
            chunks = [self._rbuf]
        else:
            chunks = []
        i = -1
        readsize = self._rbufsize
        while True:
            new = self._raw_read(readsize)
            if not new:
                break

            self.receivedbytescount += len(new)
            self._connection.receivedbytescount += len(new)
            try:
                self._handler.parent.receivedbytescount += len(new)
            except AttributeError:
                pass

            chunks.append(new)
            i = new.find(b'\n')
            if i >= 0:
                break

        # We either have exhausted the stream or have a newline in chunks[-1].

        # EOF
        if i == -1:
            self._rbuf = b''
            return b''.join(chunks)

        i += 1
        self._rbuf = chunks[-1][i:]
        chunks[-1] = chunks[-1][:i]
        return b''.join(chunks)

    def readlines(self, sizehint=0):
        total = 0
        list = []
        while True:
            line = self.readline()
            if not line:
                break
            list.append(line)
            total += len(line)
            if sizehint and total >= sizehint:
                break
        return list

    def readinto(self, dest):
        if self._raw_readinto is None:
            res = self.read(len(dest))
            if not res:
                return 0
            dest[0 : len(res)] = res
            return len(res)
        total = len(dest)
        have = len(self._rbuf)
        if have >= total:
            dest[0:total] = self._rbuf[:total]
            self._rbuf = self._rbuf[total:]
            return total
        mv = memoryview(dest)
        got = self._raw_readinto(mv[have:total])

        self.receivedbytescount += got
        self._connection.receivedbytescount += got
        try:
            self._handler.receivedbytescount += got
        except AttributeError:
            pass

        dest[0:have] = self._rbuf
        got += len(self._rbuf)
        self._rbuf = b''
        return got


def safesend(self, str):
    """Send `str' to the server.

    Shamelessly ripped off from httplib to patch a bad behavior.
    """
    # _broken_pipe_resp is an attribute we set in this function
    # if the socket is closed while we're sending data but
    # the server sent us a response before hanging up.
    # In that case, we want to pretend to send the rest of the
    # outgoing data, and then let the user use getresponse()
    # (which we wrap) to get this last response before
    # opening a new socket.
    if getattr(self, '_broken_pipe_resp', None) is not None:
        return

    if self.sock is None:
        if self.auto_open:
            self.connect()
        else:
            raise httplib.NotConnected

    # send the data to the server. if we get a broken pipe, then close
    # the socket. we want to reconnect when somebody tries to send again.
    #
    # NOTE: we DO propagate the error, though, because we cannot simply
    #       ignore the error... the caller will know if they can retry.
    if self.debuglevel > 0:
        print(b"send:", repr(str))
    try:
        blocksize = 8192
        read = getattr(str, 'read', None)
        if read is not None:
            if self.debuglevel > 0:
                print(b"sending a read()able")
            data = read(blocksize)
            while data:
                self.sock.sendall(data)
                self.sentbytescount += len(data)
                data = read(blocksize)
        else:
            self.sock.sendall(str)
            self.sentbytescount += len(str)
    except socket.error as v:
        reraise = True
        if v.args[0] == errno.EPIPE:  # Broken pipe
            if self._HTTPConnection__state == httplib._CS_REQ_SENT:
                self._broken_pipe_resp = None
                self._broken_pipe_resp = self.getresponse()
                reraise = False
            self.close()
        if reraise:
            raise


def wrapgetresponse(cls):
    """Wraps getresponse in cls with a broken-pipe sane version."""

    def safegetresponse(self):
        # In safesend() we might set the _broken_pipe_resp
        # attribute, in which case the socket has already
        # been closed and we just need to give them the response
        # back. Otherwise, we use the normal response path.
        r = getattr(self, '_broken_pipe_resp', None)
        if r is not None:
            return r
        return cls.getresponse(self)

    safegetresponse.__doc__ = cls.getresponse.__doc__
    return safegetresponse


class HTTPConnection(httplib.HTTPConnection):
    # url.httpsconnection inherits from this. So when adding/removing
    # attributes, be sure to audit httpsconnection() for unintended
    # consequences.

    # use the modified response class
    response_class = HTTPResponse
    send = safesend
    getresponse = wrapgetresponse(httplib.HTTPConnection)

    def __init__(self, *args, **kwargs):
        httplib.HTTPConnection.__init__(self, *args, **kwargs)
        self.sentbytescount = 0
        self.receivedbytescount = 0


#########################################################################
#####   TEST FUNCTIONS
#########################################################################


def continuity(url):
    md5 = hashlib.md5
    format = b'%25s: %s'

    # first fetch the file with the normal http handler
    opener = urlreq.buildopener()
    urlreq.installopener(opener)
    fo = urlreq.urlopen(url)
    foo = fo.read()
    fo.close()
    m = md5(foo)
    print(format % (b'normal urllib', hex(m.digest())))

    # now install the keepalive handler and try again
    opener = urlreq.buildopener(HTTPHandler())
    urlreq.installopener(opener)

    fo = urlreq.urlopen(url)
    foo = fo.read()
    fo.close()
    m = md5(foo)
    print(format % (b'keepalive read', hex(m.digest())))

    fo = urlreq.urlopen(url)
    foo = b''
    while True:
        f = fo.readline()
        if f:
            foo = foo + f
        else:
            break
    fo.close()
    m = md5(foo)
    print(format % (b'keepalive readline', hex(m.digest())))


def comp(N, url):
    print(b'  making %i connections to:\n  %s' % (N, url))

    procutil.stdout.write(b'  first using the normal urllib handlers')
    # first use normal opener
    opener = urlreq.buildopener()
    urlreq.installopener(opener)
    t1 = fetch(N, url)
    print(b'  TIME: %.3f s' % t1)

    procutil.stdout.write(b'  now using the keepalive handler       ')
    # now install the keepalive handler and try again
    opener = urlreq.buildopener(HTTPHandler())
    urlreq.installopener(opener)
    t2 = fetch(N, url)
    print(b'  TIME: %.3f s' % t2)
    print(b'  improvement factor: %.2f' % (t1 / t2))


def fetch(N, url, delay=0):
    import time

    lens = []
    starttime = time.time()
    for i in range(N):
        if delay and i > 0:
            time.sleep(delay)
        fo = urlreq.urlopen(url)
        foo = fo.read()
        fo.close()
        lens.append(len(foo))
    diff = time.time() - starttime

    j = 0
    for i in lens[1:]:
        j = j + 1
        if not i == lens[0]:
            print(b"WARNING: inconsistent length on read %i: %i" % (j, i))

    return diff


def test_timeout(url):
    global DEBUG
    dbbackup = DEBUG

    class FakeLogger(object):
        def debug(self, msg, *args):
            print(msg % args)

        info = warning = error = debug

    DEBUG = FakeLogger()
    print(b"  fetching the file to establish a connection")
    fo = urlreq.urlopen(url)
    data1 = fo.read()
    fo.close()

    i = 20
    print(b"  waiting %i seconds for the server to close the connection" % i)
    while i > 0:
        procutil.stdout.write(b'\r  %2i' % i)
        procutil.stdout.flush()
        time.sleep(1)
        i -= 1
    procutil.stderr.write(b'\r')

    print(b"  fetching the file a second time")
    fo = urlreq.urlopen(url)
    data2 = fo.read()
    fo.close()

    if data1 == data2:
        print(b'  data are identical')
    else:
        print(b'  ERROR: DATA DIFFER')

    DEBUG = dbbackup


def test(url, N=10):
    print(b"performing continuity test (making sure stuff isn't corrupted)")
    continuity(url)
    print(b'')
    print(b"performing speed comparison")
    comp(N, url)
    print(b'')
    print(b"performing dropped-connection check")
    test_timeout(url)


if __name__ == '__main__':
    import time

    try:
        N = int(sys.argv[1])
        url = sys.argv[2]
    except (IndexError, ValueError):
        print(b"%s <integer> <url>" % sys.argv[0])
    else:
        test(url, N)