"git replace" learned a "--graft" option to rewrite parents of a commit. * cc/replace-graft: replace: add test for --graft with a mergetag replace: check mergetags when using --graft replace: add test for --graft with signed commit replace: remove signature when using --graft contrib: add convert-grafts-to-replace-refs.sh Documentation: replace: add --graft option replace: add test for --graft replace: add --graft option replace: cleanup redirection style in tests
* kb/perf-trace: api-trace.txt: add trace API documentation progress: simplify performance measurement by using getnanotime() wt-status: simplify performance measurement by using getnanotime() git: add performance tracing for git's main() function to debug scripts trace: add trace_performance facility to debug performance issues trace: add high resolution timer function to debug performance issues trace: add 'file:line' to all trace output trace: move code around, in preparation to file:line output trace: add current timestamp to all trace output trace: disable additional trace output for unit tests trace: add infrastructure to augment trace output with additional info sha1_file: change GIT_TRACE_PACK_ACCESS logging to use trace API Documentation/git.txt: improve documentation of 'GIT_TRACE*' variables trace: improve trace performance trace: remove redundant printf format attribute trace: consistently name the format parameter trace: move trace declarations from cache.h to new trace.h
It could be misleading to keep a signature in a replacement commit, so let's remove it. Note that there should probably be a way to sign the replacement commit created when using --graft, but this can be dealt with in another commit or patch series. Signed-off-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
The trace API currently rechecks the environment variable and reopens the trace file on every API call. This has the ugly side effect that errors (e.g. file cannot be opened, or the user specified a relative path) are also reported on every call. Performance can be improved by about factor three by remembering the environment state and keeping the file open. Replace the 'const char *key' parameter in the API with a pointer to a 'struct trace_key' that bundles the environment variable name with additional, trace-internal state. Change the call sites of these APIs to use a static 'struct trace_key' instead of a string constant. In trace.c::get_trace_fd(), save and reuse the file descriptor in 'struct trace_key'. Add a 'trace_disable()' API, so that packet_trace() can cleanly disable tracing when it encounters packed data (instead of using unsetenv()). Signed-off-by: Karsten Blees <blees@dcon.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the same way as there is for_each_ref() to iterate on refs, for_each_mergetag() allows the caller to iterate on the mergetags of a given commit. Use it to rewrite show_mergetag() used in "git log". Signed-off-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we call show_signature or show_mergetag, we read the commit object fresh via read_sha1_file and reparse its headers. However, in most cases we already have the object data available, attached to the "struct commit". This is partially laziness in dealing with the memory allocation issues, but partially defensive programming, in that we would always want to verify a clean version of the buffer (not one that might have been munged by other users of the commit). However, we do not currently ever munge the commit buffer, and not using the already-available buffer carries a fairly big performance penalty when we are looking at a large number of commits. Here are timings on linux.git: [baseline, no signatures] $ time git log >/dev/null real 0m4.902s user 0m4.784s sys 0m0.120s [before] $ time git log --show-signature >/dev/null real 0m14.735s user 0m9.964s sys 0m0.944s [after] $ time git log --show-signature >/dev/null real 0m9.981s user 0m5.260s sys 0m0.936s Note that our user CPU time drops almost in half, close to the non-signature case, but we do still spend more wall-clock and system time, presumably from dealing with gpg. An alternative to this is to note that most commits do not have signatures (less than 1% in this repo), yet we pay the re-parsing cost for every commit just to find out if it has a mergetag or signature. If we checked that when parsing the commit initially, we could avoid re-examining most commits later on. Even if we did pursue that direction, however, this would still speed up the cases where we _do_ have signatures. So it's probably worth doing either way. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Most callsites which use the commit buffer try to use the cached version attached to the commit, rather than re-reading from disk. Unfortunately, that interface provides only a pointer to the NUL-terminated buffer, with no indication of the original length. For the most part, this doesn't matter. People do not put NULs in their commit messages, and the log code is happy to treat it all as a NUL-terminated string. However, some code paths do care. For example, when checking signatures, we want to be very careful that we verify all the bytes to avoid malicious trickery. This patch just adds an optional "size" out-pointer to get_commit_buffer and friends. The existing callers all pass NULL (there did not seem to be any obvious sites where we could avoid an immediate strlen() call, though perhaps with some further refactoring we could). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
This will make it easier to manage the buffer cache independently of the "struct commit" objects. It also shrinks "struct commit" by one pointer, which may be helpful. Unfortunately it does not reduce the max memory size of something like "rev-list", because rev-list uses get_cached_commit_buffer() to decide not to show each commit's output (and due to the design of slab_at, accessing the slab requires us to extend it, allocating exactly the same number of buffer pointers we dropped from the commit structs). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Like the callsites in the previous commit, logmsg_reencode already falls back to read_sha1_file when necessary. However, I split its conversion out into its own commit because it's a bit more complex. We return either: 1. The original commit->buffer 2. A newly allocated buffer from read_sha1_file 3. A reencoded buffer (based on either 1 or 2 above). while trying to do as few extra reads/allocations as possible. Callers currently free the result with logmsg_free, but we can simplify this by pointing them straight to unuse_commit_buffer. This is a slight layering violation, in that we may be passing a buffer from (3). However, since the end result is to free() anything except (1), which is unlikely to change, and because this makes the interface much simpler, it's a reasonable bending of the rules. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Many sites look at commit->buffer to get more detailed information than what is in the parsed commit struct. However, we sometimes drop commit->buffer to save memory, in which case the caller would need to read the object afresh. Some callers do this (leading to duplicated code), and others do not (which opens the possibility of a segfault if somebody else frees the buffer). Let's provide a pair of helpers, "get" and "unuse", that let callers easily get the buffer. They will use the cached buffer when possible, and otherwise load from disk using read_sha1_file. Note that we also need to add a "get_cached" variant which returns NULL when we do not have a cached buffer. At first glance this seems to defeat the purpose of "get", which is to always provide a return value. However, some log code paths actually use the NULL-ness of commit->buffer as a boolean flag to decide whether to try printing the commit. At least for now, we want to continue supporting that use. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>