view tests/test-trusted.py.out @ 26379:39d643252b9f

revlog: use existing file handle when reading during _addrevision

_addrevision() may need to read from revlogs as part of computing
deltas. Previously, we would flush existing file handles and open
a new, short-lived file handle to perform the reading.

If we have an existing file handle, it seems logical to reuse it
for reading instead of opening a new file handle. This patch
makes that the new behavior.

After this patch, revlog files are only reopened when adding
revisions if the revlog is switched from inline to non-inline.

On Linux when unbundling a bundle of the mozilla-central repo, this
patch has the following impact on system call counts:

Call     Before     After       Delta
write    827,639    673,390   -154,249
open     700,103    684,089    -16,014
read      74,489     74,489          0
fstat    493,924    461,896    -32,028
close    249,131    233,117    -16,014
stat     242,001    242,001          0
lstat     18,676     18,676          0
lseek     20,268     20,268          0
ioctl     14,652     13,173     -1,479
TOTAL  3,180,758  2,930,679   -250,079

It's worth noting that many of the open() calls fail due to missing
files. That's why there are many more open() calls than close().

Despite the significant system call reduction, this change does not
seem to have a significant performance impact on Linux.

On Windows 10 (not a VM, on a SSD), this patch appears to reduce
unbundle time for mozilla-central from ~960s to ~920s. This isn't
as significant as I was hoping. But a decrease it is nonetheless.
Still, Windows unbundle performance is still >2x slower than Linux.

Despite the lack of significant gains, fewer system calls is fewer
system calls. If nothing else, this will narrow the focus of potential
areas to optimize in the future.

# same user, same group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# same user, different group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, same group
not trusting file .hg/hgrc from untrusted user abc, group bar
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, same group, but we trust the group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, different group, but we trust the user
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, different group, but we trust the group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, different group, but we trust the user and the group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# we trust all users
# different user, different group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# we trust all groups
# different user, different group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# we trust all users and groups
# different user, different group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# we don't get confused by users and groups with the same name
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# list of user names
# different user, different group, but we trust the user
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# list of group names
# different user, different group, but we trust the group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# Can't figure out the name of the user running this process
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# prints debug warnings
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
ignoring untrusted configuration option paths.local = /another/path
    global = /some/path
untrusted
. . global = /some/path
.ignoring untrusted configuration option paths.local = /another/path
. local = /another/path

# report_untrusted enabled without debug hides warnings
# different user, different group
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# report_untrusted enabled with debug shows warnings
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
ignoring untrusted configuration option paths.local = /another/path
    global = /some/path
untrusted
. . global = /some/path
.ignoring untrusted configuration option paths.local = /another/path
. local = /another/path

# ui.readconfig sections
quux

# read trusted, untrusted, new ui, trusted
not trusting file foobar from untrusted user abc, group def
trusted:
ignoring untrusted configuration option foobar.baz = quux
None
untrusted:
quux

# error handling
# file doesn't exist
# same user, same group
# different user, different group

# parse error
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
('foo', '.hg/hgrc:1')
# same user, same group
('foo', '.hg/hgrc:1')