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Nguyễn Thái Ngọc Duy c46c406ae1 trace.h: support nested performance tracing
Performance measurements are listed right now as a flat list, which is
fine when we measure big blocks. But when we start adding more and
more measurements, some of them could be just part of a bigger
measurement and a flat list gives a wrong impression that they are
executed at the same level instead of nested.

Add trace_performance_enter() and trace_performance_leave() to allow
indent these nested measurements. For now it does not help much
because the only nested thing is (lazy) name hash initialization
(e.g. called in diff-index from "git status"). This will help more
because I'm going to add some more tracing that's actually nested.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-18 09:47:46 -07:00
Nguyễn Thái Ngọc Duy cb50761959 trace.c: export trace_setup_key
This is so that we can print traces based on this key outside trace.c.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-30 12:49:57 -07:00
Nguyễn Thái Ngọc Duy 33011e769c trace.c: move strbuf_release() out of print_trace_line()
The function is about printing a trace line, not releasing the buffer it
receives too. Move strbuf_release() back outside. This makes it easier
to see how strbuf is managed.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-16 12:16:54 -08:00
Jeff King 1fbdab21bb trace: avoid unnecessary quoting
Trace output which contains arbitrary strings (e.g., the
arguments to commands which we are running) is always passed
through sq_quote_buf(). That function always adds
single-quotes, even if the output consists of vanilla
characters. This can make the output a bit hard to read.

Let's avoid the quoting if there are no characters which a
shell would interpret. Trace output doesn't necessarily need
to be shell-compatible, but:

  - the shell language is a good ballpark for what humans
    consider readable (well, humans versed in command line
    tools)

  - the run_command bits can be cut-and-pasted to a shell,
    and we'll keep that property

  - it covers any cases which would make the output
    visually ambiguous (e.g., embedded whitespace or quotes)

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-16 12:16:54 -08:00
Jeff King e35f11c293 sq_quote_argv: drop maxlen parameter
No caller passes anything but "0" for this parameter, which
requests that the function ignore it completely. In fact, in
all of history there was only one such caller, and it went
away in 7f51f8bc2b (alias: use run_command api to execute
aliases, 2011-01-07).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-16 12:16:54 -08:00
Gennady Kupava 8eeb25c679 trace: improve performance while category is disabled
Move just enough code from trace.c into trace.h header so all code
necessary to determine that trace is disabled could be inlined to
calling functions.  Then perform the check if the trace key is
enabled sooner in call chain.

Signed-off-by: Gennady Kupava <gkupava@bloomberg.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-12-06 09:43:02 -08:00
Gennady Kupava 406102a731 trace: remove trace key normalization
Trace key normalization is not used, not strictly necessary,
complicates the code and would negatively affect compilation speed if
moved to header.

New trace_default_key key or existing separate marco could be used
instead of passing NULL as a key.

Signed-off-by: Gennady Kupava <gkupava@bloomberg.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-27 10:19:08 +09:00
Todd Zullinger 484257925f Replace Free Software Foundation address in license notices
The mailing address for the FSF has changed over the years.  Rather than
updating the address across all files, refer readers to gnu.org, as the
GNU GPL documentation now suggests for license notices.  The mailing
address is retained in the full license files (COPYING and LGPL-2.1).

The old address is still present in t/diff-lib/COPYING.  This is
intentional, as the file is used in tests and the contents are not
expected to change.

Signed-off-by: Todd Zullinger <tmz@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-09 13:21:21 +09:00
Jeff King 6f25305799 trace: do not fall back to stderr
If the trace code cannot open a specified file, or does not
understand the contents of the GIT_TRACE variable, it falls
back to printing trace output to stderr.

This is an attempt to be helpful, but in practice it just
ends up annoying. The user was trying to get the output to
go somewhere else, so spewing it to stderr does not really
accomplish that. And as it's intended for debugging, they
can presumably re-run the command with their error
corrected.

So instead of falling back, this patch disables bogus trace
keys for the rest of the program, just as we do for write
errors. We can drop the "Defaulting to..." part of the error
message entirely; after seeing "cannot open '/foo'", the
user can assume that tracing is skipped.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-05 09:28:17 -07:00
Jeff King 46ac74b716 trace: disable key after write error
If we get a write error writing to a trace descriptor, the
error isn't likely to go away if we keep writing. Instead,
you'll just get the same error over and over. E.g., try:

  GIT_TRACE_PACKET=42 git ls-remote >/dev/null

You don't really need to see:

  warning: unable to write trace for GIT_TRACE_PACKET: Bad file descriptor

hundreds of times. We could fallback to tracing to stderr,
as we do in the error code-path for open(), but there's not
much point. If the user fed us a bogus descriptor, they're
probably better off fixing their invocation. And if they
didn't, and we saw a transient error (e.g., ENOSPC writing
to a file), it probably doesn't help anybody to have half of
the trace in a file, and half on stderr.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-05 09:28:16 -07:00
Jeff King 3b0c3ab777 trace: correct variable name in write() error message
Our error message for write() always mentions GIT_TRACE,
even though we may be writing for a different variable
entirely. It's also not quite accurate to say "fd given by
GIT_TRACE environment variable", as we may hit this error
based on a filename the user put in the variable (we do
complain and switch to stderr if the file cannot be opened,
but it's still possible to hit a write() error on the
descriptor later).

So let's fix those things, and switch to our more usual
"unable to do X: Y" format for the error.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-05 09:28:16 -07:00
Jeff King b3a1c5da02 trace: cosmetic fixes for error messages
The error messages for the trace code are often multi-line;
the first line gets a nice "warning:", but the rest are
left-aligned. Let's give them an indentation to make sure
they stand out as a unit.

While we're here, let's also downcase the first letter of
each error (our usual style), and break up a long line of
advice (since we're already using multiple lines, one more
doesn't hurt).

We also replace "What does 'foo' for GIT_TRACE mean?". While
cute, it's probably a good idea to give more context, and
follow our usual styles. So it's now "unknown trace value
for 'GIT_TRACE': foo".

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-05 09:28:16 -07:00
Jeff King 38f460caa2 trace: use warning() for printing trace errors
Right now we just fprintf() straight to stderr, which can
make the output hard to distinguish. It would be helpful to
give it one of our usual prefixes like "error:", "warning:",
etc.

It doesn't make sense to use error() here, as the trace code
is "optional" debugging code. If something goes wrong, we
should warn the user, but saying "error" implies the actual
git operation had a problem. So warning() is the only sane
choice.

Note that this does end up calling warn_routine() to do the
formatting. This is probably a good thing, since they are
clearly trying to hook messages before they make it to
stderr. However, it also means that in theory somebody who
tries to trace from their warn_routine() could cause a loop.
This seems rather unlikely in practice (we've never even
overridden the default warn_builtin routine before, and
recent discussions to do so would just install a noop
routine).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-05 09:27:34 -07:00
Jeff King c0222e762e trace: stop using write_or_whine_pipe()
The write_or_whine_pipe function does two things:

  1. it checks for EPIPE and converts it into a signal death

  2. it prints a message to stderr on error

The first thing does not help us, and actively hurts.
Generally we would simply die from SIGPIPE in this case,
unless somebody has taken the time to ignore SIGPIPE for the
whole process.  And if they _did_ do that, it seems rather
silly for the trace code, which otherwise takes pains to
continue even in the face of errors (e.g., by not using
write_or_die!), to take down the whole process for one
specific type of error.

Nor does the second thing help us; it just makes it harder
to write our error message, because we have to feed bits of
it as an argument to write_or_whine_pipe(). Translators
never get to see the full message, and it's hard for us to
customize it.

Let's switch to just using write_in_full() and writing our
own error string. For now, the error is identical to what
write_or_whine_pipe() would say, but now that it's more
under our control, we can improve it in future patches.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-04 13:33:27 -07:00
Jeff King c81539b5f6 trace: handle NULL argument in trace_disable()
All of the trace functions treat a NULL key as a synonym for
the default GIT_TRACE key. Except for trace_disable(), which
will segfault.

Fortunately, this can't cause any bugs, as the function has
no callers. But rather than drop it, let's fix the bug, as I
plan to add a caller.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-04 13:33:27 -07:00
Jeff King 0bb443fdd2 trace: use strbuf for quote_crnl output
When we output GIT_TRACE_SETUP paths, we quote any
meta-characters. But our buffer to hold the result is only
PATH_MAX bytes, and we could double the size of the input
path (if every character needs quoting). We could use a
2*PATH_MAX buffer, if we assume the input will never be more
than PATH_MAX. But it's easier still to just switch to a
strbuf and not worry about whether the input can exceed
PATH_MAX or not.

The original copied the "p2" pointer to "p1", advancing
both. Since this gets rid of "p1", let's also drop "p2",
whose name is now confusing. We can just advance the
original "path" pointer.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-25 10:18:18 -07:00
Jeff King 323598387d pkt-line: support tracing verbatim pack contents
When debugging the pack protocol, it is sometimes useful to
store the verbatim pack that we sent or received on the
wire. Looking at the on-disk result is often not helpful for
a few reasons:

  1. If the operation is a clone, we destroy the repo on
     failure, leaving nothing on disk.

  2. If the pack is small, we unpack it immediately, and the
     full pack never hits the disk.

  3. If we feed the pack to "index-pack --fix-thin", the
     resulting pack has the extra delta bases added to it.

We already have a GIT_TRACE_PACKET mechanism for tracing
packets. Let's extend it with GIT_TRACE_PACKFILE to dump the
verbatim packfile.

There are a few other positive fallouts that come from
rearranging this code:

 - We currently disable the packet trace after seeing the
   PACK header, even though we may get human-readable lines
   on other sidebands; now we include them in the trace.

 - We currently try to print "PACK ..." in the trace to
   indicate that the packfile has started. But because we
   disable packet tracing, we never printed this line. We
   will now do so.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-06-16 13:24:22 -07:00
Junio C Hamano 68a2e6a2c8 Merge branch 'nd/multiple-work-trees'
A replacement for contrib/workdir/git-new-workdir that does not
rely on symbolic links and make sharing of objects and refs safer
by making the borrowee and borrowers aware of each other.

* nd/multiple-work-trees: (41 commits)
  prune --worktrees: fix expire vs worktree existence condition
  t1501: fix test with split index
  t2026: fix broken &&-chain
  t2026 needs procondition SANITY
  git-checkout.txt: a note about multiple checkout support for submodules
  checkout: add --ignore-other-wortrees
  checkout: pass whole struct to parse_branchname_arg instead of individual flags
  git-common-dir: make "modules/" per-working-directory directory
  checkout: do not fail if target is an empty directory
  t2025: add a test to make sure grafts is working from a linked checkout
  checkout: don't require a work tree when checking out into a new one
  git_path(): keep "info/sparse-checkout" per work-tree
  count-objects: report unused files in $GIT_DIR/worktrees/...
  gc: support prune --worktrees
  gc: factor out gc.pruneexpire parsing code
  gc: style change -- no SP before closing parenthesis
  checkout: clean up half-prepared directories in --to mode
  checkout: reject if the branch is already checked out elsewhere
  prune: strategies for linked checkouts
  checkout: support checking out into a new working directory
  ...
2015-05-11 14:23:39 -07:00
Reuben Hawkins a6c3c638ac configure.ac: check for clock_gettime and CLOCK_MONOTONIC
Set or clear Makefile variables HAVE_CLOCK_GETTIME and
HAVE_CLOCK_MONOTONIC based upon results of the checks (overriding
default values from config.mak.uname).

CLOCK_MONOTONIC isn't available on RHEL3, but there are still RHEL3
systems being used in production.

Signed-off-by: Reuben Hawkins <reubenhwk@gmail.com>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-01-09 15:33:39 -08:00
Junio C Hamano a305b15f82 Merge branch 'rs/use-strbuf-complete-line'
* rs/use-strbuf-complete-line:
  use strbuf_complete_line() for adding a newline if needed
2014-12-22 12:28:22 -08:00
René Scharfe a0d4923ddf use strbuf_complete_line() for adding a newline if needed
Call strbuf_complete_line() instead of open-coding it.  Also remove
surrounding comments indicating the intent to complete a line since
this information is already included in the function name.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-12-12 11:23:45 -08:00
Nguyễn Thái Ngọc Duy 31e26ebcb5 setup.c: support multi-checkout repo setup
The repo setup procedure is updated to detect $GIT_DIR/commondir and
set $GIT_COMMON_DIR properly.

The core.worktree is ignored when $GIT_COMMON_DIR is set. This is
because the config file is shared in multi-checkout setup, but
checkout directories _are_ different. Making core.worktree effective
in all checkouts mean it's back to a single checkout.

Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-12-01 11:00:15 -08:00
Junio C Hamano c11dc64722 Merge branch 'bw/trace-no-inline-getnanotime'
No file-scope static variables in an inlined function, please.

* bw/trace-no-inline-getnanotime:
  trace.c: do not mark getnanotime() as "inline"
2014-10-16 14:16:45 -07:00
Ben Walton 6433d56975 trace.c: do not mark getnanotime() as "inline"
Oracle Studio compilers don't allow for static variables in
functions that are defined to be inline. GNU C does permit this.

Let's reference the C99 standard though, which doesn't allow for
inline functions to contain modifiable static variables.

Signed-off-by: Ben Walton <bdwalton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-29 16:13:58 -07:00
Junio C Hamano 9ee9c9d068 Merge branch 'kb/perf-trace'
Compilation fix for some compilers.

* kb/perf-trace:
  trace: correct trace_strbuf() parameter type for !HAVE_VARIADIC_MACROS
2014-09-19 11:38:39 -07:00
René Scharfe 792a646a19 trace: correct trace_strbuf() parameter type for !HAVE_VARIADIC_MACROS
Reported-by: dev <dev@cor0.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-08 11:08:04 -07:00
Junio C Hamano f655651e09 Merge branch 'rs/strbuf-getcwd'
Reduce the use of fixed sized buffer passed to getcwd() calls
by introducing xgetcwd() helper.

* rs/strbuf-getcwd:
  use strbuf_add_absolute_path() to add absolute paths
  abspath: convert absolute_path() to strbuf
  use xgetcwd() to set $GIT_DIR
  use xgetcwd() to get the current directory or die
  wrapper: add xgetcwd()
  abspath: convert real_path_internal() to strbuf
  abspath: use strbuf_getcwd() to remember original working directory
  setup: convert setup_git_directory_gently_1 et al. to strbuf
  unix-sockets: use strbuf_getcwd()
  strbuf: add strbuf_getcwd()
2014-09-02 13:28:44 -07:00
René Scharfe 56b9f6e738 use xgetcwd() to get the current directory or die
Convert several calls of getcwd() and die() to use xgetcwd() instead.
This way we get rid of fixed-size buffers (which can be too small
depending on the used file system) and gain consistent error messages.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-08-26 11:06:06 -07:00
Karsten Blees 578da0391a git: add performance tracing for git's main() function to debug scripts
Use trace_performance to measure and print execution time and command line
arguments of the entire main() function. In constrast to the shell's 'time'
utility, which measures total time of the parent process, this logs all
involved git commands recursively. This is particularly useful to debug
performance issues of scripted commands (i.e. which git commands were
called with which parameters, and how long did they execute).

Due to git's deliberate use of exit(), the implementation uses an atexit
routine rather than just adding trace_performance_since() at the end of
main().

Usage example: > GIT_TRACE_PERFORMANCE=~/git-trace.log git stash list

Creates a log file like this:
23:57:38.638765 trace.c:405 performance: 0.000310107 s: git command: 'git' 'rev-parse' '--git-dir'
23:57:38.644387 trace.c:405 performance: 0.000261759 s: git command: 'git' 'rev-parse' '--show-toplevel'
23:57:38.646207 trace.c:405 performance: 0.000304468 s: git command: 'git' 'config' '--get-colorbool' 'color.interactive'
23:57:38.648491 trace.c:405 performance: 0.000241667 s: git command: 'git' 'config' '--get-color' 'color.interactive.help' 'red bold'
23:57:38.650465 trace.c:405 performance: 0.000243063 s: git command: 'git' 'config' '--get-color' '' 'reset'
23:57:38.654850 trace.c:405 performance: 0.025126313 s: git command: 'git' 'stash' 'list'

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:25:21 -07:00
Karsten Blees 09b2c1c769 trace: add trace_performance facility to debug performance issues
Add trace_performance and trace_performance_since macros that print a
duration and an optional printf-formatted text to the file specified in
environment variable GIT_TRACE_PERFORMANCE.

These macros, in conjunction with getnanotime(), are intended to simplify
performance measurements from within the application (i.e. profiling via
manual instrumentation, rather than using an external profiling tool).

Unless enabled via GIT_TRACE_PERFORMANCE, these macros have no noticeable
impact on performance, so that test code for well known time killers may
be shipped in release builds. Alternatively, a developer could provide an
additional performance patch (not meant for master) that allows reviewers
to reproduce performance tests more easily, e.g. on other platforms or
using their own repositories.

Usage examples:

Simple use case (measure one code section):

  uint64_t start = getnanotime();
  /* code section to measure */
  trace_performance_since(start, "foobar");

Complex use case (measure repetitive code sections):

  uint64_t t = 0;
  for (;;) {
    /* ignore */
    t -= getnanotime();
    /* code section to measure */
    t += getnanotime();
    /* ignore */
  }
  trace_performance(t, "frotz");

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:25:20 -07:00
Karsten Blees 148d6771bf trace: add high resolution timer function to debug performance issues
Add a getnanotime() function that returns nanoseconds since 01/01/1970 as
unsigned 64-bit integer (i.e. overflows in july 2554). This is easier to
work with than e.g. struct timeval or struct timespec. Basing the timer on
the epoch allows using the results with other time-related APIs.

To simplify adaption to different platforms, split the implementation into
a common getnanotime() and a platform-specific highres_nanos() function.

The common getnanotime() function handles errors, falling back to
gettimeofday() if highres_nanos() isn't implemented or doesn't work.

getnanotime() is also responsible for normalizing to the epoch. The offset
to the system clock is calculated only once on initialization, i.e.
manually setting the system clock has no impact on the timer (except if
the fallback gettimeofday() is in use). Git processes are typically short
lived, so we don't need to handle clock drift.

The highres_nanos() function returns monotonically increasing nanoseconds
relative to some arbitrary point in time (e.g. system boot), or 0 on
failure. Providing platform-specific implementations should be relatively
easy, e.g. adapting to clock_gettime() as defined by the POSIX realtime
extensions is seven lines of code.

This version includes highres_nanos() implementations for:
 * Linux: using clock_gettime(CLOCK_MONOTONIC)
 * Windows: using QueryPerformanceCounter()

Todo:
 * enable clock_gettime() on more platforms
 * add Mac OSX version, e.g. using mach_absolute_time + mach_timebase_info

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:25:20 -07:00
Karsten Blees e05bed960d trace: add 'file:line' to all trace output
This is useful to see where trace output came from.

Add 'const char *file, int line' parameters to the printing functions and
rename them to *_fl.

Add trace_printf* and trace_strbuf macros resolving to the *_fl functions
and let the preprocessor fill in __FILE__ and __LINE__.

As the trace_printf* functions take a variable number of arguments, this
requires variadic macros (i.e. '#define foo(...) foo_impl(__VA_ARGS__)'.
Though part of C99, it is unclear whether older compilers support this.
Thus keep the old functions and only enable variadic macros for GNUC and
MSVC 2005+ (_MSC_VER 1400). This has the nice side effect that the old
C-style declarations serve as documentation how the macros are to be used.

Print 'file:line ' as prefix to each trace line. Align the remaining trace
output at column 40 to accommodate 18 char file names + 4 digit line
number (currently there are 30 *.c files of length 18 and just 11 of 19).
Trace output from longer source files (e.g. builtin/receive-pack.c) will
not be aligned.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:25:20 -07:00
Karsten Blees 66f66c596f trace: move code around, in preparation to file:line output
No functional changes, just move stuff around so that the next patch isn't
that ugly...

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:25:19 -07:00
Karsten Blees b72be02cfb trace: add current timestamp to all trace output
This is useful to tell apart trace output of separate test runs.

It can also be used for basic, coarse-grained performance analysis. Note
that the accuracy is tainted by writing to the trace file, and you have to
calculate the deltas yourself (which is next to impossible if multiple
threads or processes are involved).

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:25:19 -07:00
Karsten Blees 124647c4b0 trace: disable additional trace output for unit tests
Some unit-tests use trace output to verify internal state, and unstable
output such as timestamps and line numbers are not useful there.

Disable additional trace output if GIT_TRACE_BARE is set.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:25:19 -07:00
Karsten Blees c69dfd24db trace: add infrastructure to augment trace output with additional info
To be able to add a common prefix or suffix to all trace output (e.g.
a timestamp or file:line of the caller), factor out common setup and
cleanup tasks of the trace* functions.

When adding a common prefix, it makes sense that the output of each trace
call starts on a new line. Add '\n' in case the caller forgot.

Note that this explicitly limits trace output to line-by-line, it is no
longer possible to trace-print just part of a line. Until now, this was
just an implicit assumption (trace-printing part of a line worked, but
messed up the trace file if multiple threads or processes were involved).

Thread-safety / inter-process-safety is also the reason why we need to do
the prefixing and suffixing in memory rather than issuing multiple write()
calls. Write_or_whine_pipe() / xwrite() is atomic unless the size exceeds
MAX_IO_SIZE (8MB, see wrapper.c). In case of trace_strbuf, this costs an
additional string copy (which should be irrelevant for performance in light
of actual file IO).

While we're at it, rename trace_strbuf's 'buf' argument, which suggests
that the function is modifying the buffer. Trace_strbuf() currently is the
only trace API that can print arbitrary binary data (without barfing on
'%' or stopping at '\0'), so 'data' seems more appropriate.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-13 21:25:18 -07:00
Karsten Blees 6aa3085702 trace: improve trace performance
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>
2014-07-13 21:24:23 -07:00
Karsten Blees 0d0424272f trace: remove redundant printf format attribute
trace_printf_key() is the only non-static function that duplicates the
printf format attribute in the .c file, remove it for consistency.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-06-17 09:37:47 -07:00
Karsten Blees 4a3b0b25f1 trace: consistently name the format parameter
The format parameter to trace_printf functions is sometimes abbreviated
'fmt'. Rename to 'format' everywhere (consistent with POSIX' printf
specification).

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-06-17 09:37:47 -07:00
Nguyễn Thái Ngọc Duy 58babfffde shallow.c: the 8 steps to select new commits for .git/shallow
Suppose a fetch or push is requested between two shallow repositories
(with no history deepening or shortening). A pack that contains
necessary objects is transferred over together with .git/shallow of
the sender. The receiver has to determine whether it needs to update
.git/shallow if new refs needs new shallow comits.

The rule here is avoid updating .git/shallow by default. But we don't
want to waste the received pack. If the pack contains two refs, one
needs new shallow commits installed in .git/shallow and one does not,
we keep the latter and reject/warn about the former.

Even if .git/shallow update is allowed, we only add shallow commits
strictly necessary for the former ref (remember the sender can send
more shallow commits than necessary) and pay attention not to
accidentally cut the receiver history short (no history shortening is
asked for)

So the steps to figure out what ref need what new shallow commits are:

1. Split the sender shallow commit list into "ours" and "theirs" list
   by has_sha1_file. Those that exist in current repo in "ours", the
   remaining in "theirs".

2. Check the receiver .git/shallow, remove from "ours" the ones that
   also exist in .git/shallow.

3. Fetch the new pack. Either install or unpack it.

4. Do has_sha1_file on "theirs" list again. Drop the ones that fail
   has_sha1_file. Obviously the new pack does not need them.

5. If the pack is kept, remove from "ours" the ones that do not exist
   in the new pack.

6. Walk the new refs to answer the question "what shallow commits,
   both ours and theirs, are required in .git/shallow in order to add
   this ref?". Shallow commits not associated to any refs are removed
   from their respective list.

7. (*) Check reachability (from the current refs) of all remaining
   commits in "ours". Those reachable are removed. We do not want to
   cut any part of our (reachable) history. We only check up
   commits. True reachability test is done by
   check_everything_connected() at the end as usual.

8. Combine the final "ours" and "theirs" and add them all to
   .git/shallow. Install new refs. The case where some hook rejects
   some refs on a push is explained in more detail in the push
   patches.

Of these steps, #6 and #7 are expensive. Both require walking through
some commits, or in the worst case all commits. And we rather avoid
them in at least common case, where the transferred pack does not
contain any shallow commits that the sender advertises. Let's look at
each scenario:

1) the sender has longer history than the receiver

   All shallow commits from the sender will be put into "theirs" list
   at step 1 because none of them exists in current repo. In the
   common case, "theirs" becomes empty at step 4 and exit early.

2) the sender has shorter history than the receiver

   All shallow commits from the sender are likely in "ours" list at
   step 1. In the common case, if the new pack is kept, we could empty
   "ours" and exit early at step 5.

   If the pack is not kept, we hit the expensive step 6 then exit
   after "ours" is emptied. There'll be only a handful of objects to
   walk in fast-forward case. If it's forced update, we may need to
   walk to the bottom.

3) the sender has same .git/shallow as the receiver

   This is similar to case 2 except that "ours" should be emptied at
   step 2 and exit early.

A fetch after "clone --depth=X" is case 1. A fetch after "clone" (from
a shallow repo) is case 3. Luckily they're cheap for the common case.

A push from "clone --depth=X" falls into case 2, which is expensive.
Some more work may be done at the sender/client side to avoid more
work on the server side: if the transferred pack does not contain any
shallow commits, send-pack should not send any shallow commits to the
receive-pack, effectively turning it into a normal push and avoid all
steps.

This patch implements all steps except #3, already handled by
fetch-pack and receive-pack, #6 and #7, which has their own patch due
to their size.

(*) in previous versions step 7 was put before step 3. I reorder it so
    that the common case that keeps the pack does not need to walk
    commits at all. In future if we implement faster commit
    reachability check (maybe with the help of pack bitmaps or commit
    cache), step 7 could become cheap and be moved up before 6 again.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-12-10 16:14:16 -08:00
Jeff King 4621085b7e add missing "format" function attributes
For most of our functions that take printf-like formats, we
use gcc's __attribute__((format)) to get compiler warnings
when the functions are misused. Let's give a few more
functions the same protection.

In most cases, the annotations do not uncover any actual
bugs; the only code change needed is that we passed a size_t
to transfer_debug, which expected an int. Since we expect
the passed-in value to be a relatively small buffer size
(and cast a similar value to int directly below), we can
just cast away the problem.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-07-09 22:23:04 -07:00
Junio C Hamano cbfb93a12b trace.c: mark a private file-scope symbol as static
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-09-15 22:58:21 -07:00
Stephen Boyd c2e86addb8 Fix sparse warnings
Fix warnings from 'make check'.

 - These files don't include 'builtin.h' causing sparse to complain that
   cmd_* isn't declared:

   builtin/clone.c:364, builtin/fetch-pack.c:797,
   builtin/fmt-merge-msg.c:34, builtin/hash-object.c:78,
   builtin/merge-index.c:69, builtin/merge-recursive.c:22
   builtin/merge-tree.c:341, builtin/mktag.c:156, builtin/notes.c:426
   builtin/notes.c:822, builtin/pack-redundant.c:596,
   builtin/pack-refs.c:10, builtin/patch-id.c:60, builtin/patch-id.c:149,
   builtin/remote.c:1512, builtin/remote-ext.c:240,
   builtin/remote-fd.c:53, builtin/reset.c:236, builtin/send-pack.c:384,
   builtin/unpack-file.c:25, builtin/var.c:75

 - These files have symbols which should be marked static since they're
   only file scope:

   submodule.c:12, diff.c:631, replace_object.c:92, submodule.c:13,
   submodule.c:14, trace.c:78, transport.c:195, transport-helper.c:79,
   unpack-trees.c:19, url.c:3, url.c:18, url.c:104, url.c:117, url.c:123,
   url.c:129, url.c:136, thread-utils.c:21, thread-utils.c:48

 - These files redeclare symbols to be different types:

   builtin/index-pack.c:210, parse-options.c:564, parse-options.c:571,
   usage.c:49, usage.c:58, usage.c:63, usage.c:72

 - These files use a literal integer 0 when they really should use a NULL
   pointer:

   daemon.c:663, fast-import.c:2942, imap-send.c:1072, notes-merge.c:362

While we're in the area, clean up some unused #includes in builtin files
(mostly exec_cmd.h).

Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-03-22 10:16:54 -07:00
Jeff King 7e2342d098 trace: give repo_setup trace its own key
You no longer get this output with GIT_TRACE=1; instead, you
can do GIT_TRACE_SETUP=1.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-03-08 12:12:04 -08:00
Jeff King 94b3b37464 trace: add trace_strbuf
If you happen to have a strbuf, it is a little more readable
and a little more efficient to be able to print it directly
instead of jamming it through the trace_printf interface.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-03-08 12:12:04 -08:00
Jeff King 39bc5e4680 trace: factor out "do we want to trace" logic
As we add more tracing areas, this will avoid repeated code.

Technically, trace_printf already checks this and will avoid
printing if the trace key is not set. However, callers may
want to find out early whether or not tracing is enabled so
they can avoid doing work in the common non-trace case.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-03-08 12:12:04 -08:00
Jeff King 06796607ef trace: refactor to support multiple env variables
Right now you turn all tracing off and on with GIT_TRACE. To
support new types of tracing without forcing the user to see
all of them, we will soon support turning each tracing area
on with GIT_TRACE_*.

This patch lays the groundwork by providing an interface
which does not assume GIT_TRACE. However, we still maintain
the trace_printf interface so that existing callers do not
need to be refactored.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-03-08 12:12:04 -08:00
Jeff King c6053543f2 trace: add trace_vprintf
This is a necessary cleanup to adding new types of trace
functions.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-03-08 12:12:04 -08:00
Jeff King ebeb60900f strbuf: add strbuf_vaddf
In a variable-args function, the code for writing into a strbuf is
non-trivial. We ended up cutting and pasting it in several places
because there was no vprintf-style function for strbufs (which in turn
was held up by a lack of va_copy).

Now that we have a fallback va_copy, we can add strbuf_vaddf, the
strbuf equivalent of vsprintf. And we can clean up the cut and paste
mess.

Signed-off-by: Jeff King <peff@peff.net>
Improved-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-02-26 01:06:50 -08:00
Brandon Casey e83c267f71 trace.c: ensure NULL is not passed to printf
GNU printf, and many others, will print the string "(null)" if a NULL
pointer is passed as the argument to a "%s" format specifier.  Some
implementations (like on Solaris) do not detect a NULL pointer and will
produce a segfault in this case.

So, fix this by ensuring that pointer variables do not contain the value
NULL.  Assign the string "(null)" to the variables are NULL.

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-01-06 12:21:49 -08:00