git/fetch-pack.c, branch v2.10.2

fetch-pack: do not reset in_vain on non-novel acks

2016-09-23T19:37:45Z

The MAX_IN_VAIN mechanism was introduced in commit f061e5f ("fetch-pack: give up after getting too many "ack continue"", 2006-05-24) to stop ref negotiation if a number of consecutive "have"s have been sent with no corresponding new acks. This is to stop the client from digging too deep in an irrelevant side branch in vain without ever finding a common ancestor. A use case (as described in that commit) is the scenario in which the local repository has more roots than the remote repository. However, during a negotiation in which stateless RPCs are used, MAX_IN_VAIN will (almost) never trigger (in the more-roots scenario above and others) because in each new request, the client has to inform the server of objects it already has and knows the server has (to remind the server of the state), which the server then acks. Make fetch-pack only consider, as new acks for the purpose of MAX_IN_VAIN, acks for objects for which the client has never received an ack before in this session. Signed-off-by: Jonathan Tan Signed-off-by: Junio C Hamano

fetch-pack: grow stateless RPC windows exponentially

2016-07-19T20:27:22Z

When updating large repositories, the LARGE_FLUSH limit (that is, the limit at which the window growth strategy switches from exponential to linear) is reached quite quickly. Use a conservative exponential growth strategy when that limit is reached instead (and increase LARGE_FLUSH so that there is no regression in window size). This optimization is only applied during stateless RPCs to avoid the issue raised and fixed in commit 44d8dc54 (Fix potential local deadlock during fetch-pack, 2011-03-29). Signed-off-by: Jonathan Tan Reviewed-by: Jonathan Nieder Signed-off-by: Junio C Hamano

fetch-pack: isolate sigpipe in demuxer thread

2016-04-20T20:33:56Z

In commit 9ff18fa (fetch-pack: ignore SIGPIPE in sideband demuxer, 2016-02-24), we started using sigchain_push() to ignore SIGPIPE in the async demuxer thread. However, this is rather clumsy, as it ignores SIGPIPE for the entire process, including the main thread. At the time we didn't have any per-thread signal support, but we now we do. Let's use it. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

fetch-pack: ignore SIGPIPE in sideband demuxer

2016-02-25T21:51:47Z

If the other side feeds us a bogus pack, index-pack (or unpack-objects) may die early, before consuming all of its input. As a result, the sideband demuxer may get SIGPIPE (racily, depending on whether our data made it into the pipe buffer or not). If this happens and we are compiled with pthread support, it will take down the main thread, too. This isn't the end of the world, as the main process will just die() anyway when it sees index-pack failed. But it does mean we don't get a chance to say "fatal: index-pack failed" or similar. And it also means that we racily fail t5504, as we sometimes die() and sometimes are killed by SIGPIPE. So let's ignore SIGPIPE while demuxing the sideband. We are already careful to check the return value of write(), so we won't waste time writing to a broken pipe. The caller will notice the error return from the async thread, though in practice we don't even get that far, as we die() as soon as we see that index-pack failed. The non-sideband case is already fine; we let index-pack read straight from the socket, so there is no SIGPIPE at all. Technically the non-threaded async case is also OK without this (the forked async process gets SIGPIPE), but it's not worth distinguishing from the threaded case here. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Remove get_object_hash.

2015-11-20T13:02:05Z

Convert all instances of get_object_hash to use an appropriate reference to the hash member of the oid member of struct object. This provides no functional change, as it is essentially a macro substitution. Signed-off-by: brian m. carlson Signed-off-by: Jeff King

Convert struct object to object_id

2015-11-20T13:02:05Z

struct object is one of the major data structures dealing with object IDs. Convert it to use struct object_id instead of an unsigned char array. Convert get_object_hash to refer to the new member as well. Signed-off-by: brian m. carlson Signed-off-by: Jeff King

Add several uses of get_object_hash.

2015-11-20T13:02:05Z

Convert most instances where the sha1 member of struct object is dereferenced to use get_object_hash. Most instances that are passed to functions that have versions taking struct object_id, such as get_sha1_hex/get_oid_hex, or instances that can be trivially converted to use struct object_id instead, are not converted. Signed-off-by: brian m. carlson Signed-off-by: Jeff King

Convert struct ref to use object_id.

2015-11-20T13:02:05Z

Use struct object_id in three fields in struct ref and convert all the necessary places that use it. Signed-off-by: brian m. carlson Signed-off-by: Jeff King

fetch-pack: use argv_array for index-pack / unpack-objects

2015-10-05T18:08:05Z

This cleans up a magic number that must be kept in sync with the rest of the code (the number of argv slots). It also lets us drop some fixed buffers and an sprintf (since we can now use argv_array_pushf). We do still have to keep one fixed buffer for calling gethostname, but at least now the size computations for it are much simpler. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

memoize common git-path "constant" files

2015-08-10T22:37:14Z

One of the most common uses of git_path() is to pass a constant, like git_path("MERGE_MSG"). This has two drawbacks: 1. The return value is a static buffer, and the lifetime is dependent on other calls to git_path, etc. 2. There's no compile-time checking of the pathname. This is OK for a one-off (after all, we have to spell it correctly at least once), but many of these constant strings appear throughout the code. This patch introduces a series of functions to "memoize" these strings, which are essentially globals for the lifetime of the program. We compute the value once, take ownership of the buffer, and return the cached value for subsequent calls. cache.h provides a helper macro for defining these functions as one-liners, and defines a few common ones for global use. Using a macro is a little bit gross, but it does nicely document the purpose of the functions. If we need to touch them all later (e.g., because we learned how to change the git_dir variable at runtime, and need to invalidate all of the stored values), it will be much easier to have the complete list. Note that the shared-global functions have separate, manual declarations. We could do something clever with the macros (e.g., expand it to a declaration in some places, and a declaration _and_ a definition in path.c). But there aren't that many, and it's probably better to stay away from too-magical macros. Likewise, if we abandon the C preprocessor in favor of generating these with a script, we could get much fancier. E.g., normalizing "FOO/BAR-BAZ" into "git_path_foo_bar_baz". But the small amount of saved typing is probably not worth the resulting confusion to readers who want to grep for the function's definition. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano