transaction: introduce a transaction ID, to be available to all hooks The transaction ID is built from the object ID and creation time stamp to make sure it is unique.

transaction: actually use tr.hookargs in pretxnclose The 'tr.hookargs' is a dictionary containing all the arguments to be passed to hooks. It is actually used for hooks now...

bundle2: use unbundle source as transaction name This is what a bundle 1 push is doing. This got caught by trying to run the whole test-suite using bundle2 for exchanges.

tags: have a different cache file per filter level Currently whichever filter level asks for tags last will write the data on disk. This create massive issues when tags are read for "visible" and "unfiltered" on large and multi headed repository (like Mozilla central). See issue4550 for details Each filter level recomputes its own cache without direct collaboration but they all share the same 'hgtagsfnodes' cache. And that is where most of the time is spent.

parsers: when available, use a presized dictionary for the file foldmap On a repo with over 300,000 files, this speeds up perffilefoldmap: before: wall 0.178421 comb 0.180000 user 0.160000 sys 0.020000 (best of 55) after: wall 0.164462 comb 0.160000 user 0.140000 sys 0.020000 (best of 59)

tags: extract .hgtags filenodes cache to a standalone file Resolution of .hgtags filenodes values has historically been a performance pain point for large repositories, where reading individual manifests can take over 100ms. Multiplied by hundreds or even thousands of heads and resolving .hgtags filenodes becomes a performance issue. This patch establishes a standalone cache file holding the .hgtags filenodes for each changeset. After this patch, the .hgtags filenode for any particular changeset should only have to be computed once during the lifetime of the repository. The introduced hgtagsfnodes1 cache file is modeled after the rev branch cache: the cache is effectively an array of entries consisting of a changeset fragment and the filenode for a revision. The file grows in proportion to the length of the repository (24 bytes per changeset) and is truncated when the repository is stripped. The file is not written unless tag info is requested and tags have changed since last time. This patch partially addresses issue4550. Future patches will split the "tags" cache file into per-filter files and will refactor the cache format to not capture the .hgtags fnodes, as these are now stored in the hgtagsfnodes1 cache. This patch is capable of standing alone. We should not have to wait on the tags cache filter split and format refactor for this patch to land.

extensions: extract partial application into a bind() function We use partial function application for wrapping existing Mercurial functions, and it's implemented separately each time. This patch extracts the partial application into a new bind() function that can be used on its own by extensions when appropriate. In particular, the evolve extension needs to wrap functions in the various bundle2 processing dictionaries, which the pre-existing methods don't support.