5f44324 (core: log offset pack data accesses happened - 2011-07-06)
provides a way to observe pack access patterns via a config
switch. Setting an environment variable looks more obvious than a
config var, especially when you just need to _observe_, and more
inline with other tracing knobs we have.
Document it as it may be useful for remote troubleshooting.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
Documentation/git.txt | 7 +++++++
cache.h | 3 ---
config.c | 3 ---
environment.c | 1 -
sha1_file.c | 14 ++++++++++++--
5 files changed, 19 insertions(+), 9 deletions(-)
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 68f1ee6..c760918 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -838,6 +838,13 @@ for further details.
as a file path and will try to write the trace messages
into it.
+'GIT_TRACE_PACK_ACCESS'::
+ If this variable is set to a path, a file will be created at
+ the given path logging all accesses to any packs. For each
+ access, the pack file name and an offset in the pack is
+ recorded. This may be helpful for troubleshooting some
+ pack-related performance problems.
+
GIT_LITERAL_PATHSPECS::
Setting this variable to `1` will cause Git to treat all
pathspecs literally, rather than as glob patterns. For example,
diff --git a/cache.h b/cache.h
index df532f8..4f41606 100644
--- a/cache.h
+++ b/cache.h
@@ -772,9 +772,6 @@ extern int parse_sha1_header(const char *hdr, unsigned long *sizep);
/* global flag to enable extra checks when accessing packed objects */
extern int do_check_packed_object_crc;
-/* for development: log offset of pack access */
-extern const char *log_pack_access;
-
extern int check_sha1_signature(const unsigned char *sha1, void *buf, unsigned long size, const char *type);
extern int move_temp_to_file(const char *tmpfile, const char *filename);
diff --git a/config.c b/config.c
index 7a85ebd..d04e815 100644
--- a/config.c
+++ b/config.c
@@ -688,9 +688,6 @@ static int git_default_core_config(const char *var, const char *value)
return 0;
}
- if (!strcmp(var, "core.logpackaccess"))
- return git_config_string(&log_pack_access, var, value);
-
if (!strcmp(var, "core.autocrlf")) {
if (value && !strcasecmp(value, "input")) {
if (core_eol == EOL_CRLF)
diff --git a/environment.c b/environment.c
index e2e75c1..0cb67b2 100644
--- a/environment.c
+++ b/environment.c
@@ -37,7 +37,6 @@ size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
size_t delta_base_cache_limit = 16 * 1024 * 1024;
unsigned long big_file_threshold = 512 * 1024 * 1024;
-const char *log_pack_access;
const char *pager_program;
int pager_use_color = 1;
const char *editor_program;
diff --git a/sha1_file.c b/sha1_file.c
index b114cc9..4b23bb8 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -36,6 +36,9 @@ static inline uintmax_t sz_fmt(size_t s) { return s; }
const unsigned char null_sha1[20];
+static const char *no_log_pack_access = "no_log_pack_access";
+static const char *log_pack_access;
+
/*
* This is meant to hold a *small* number of objects that you would
* want read_sha1_file() to be able to return, but yet you do not want
@@ -1956,12 +1959,19 @@ static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
{
static FILE *log_file;
+ if (!log_pack_access)
+ log_pack_access = getenv("GIT_TRACE_PACK_ACCESS");
+ if (!log_pack_access)
+ log_pack_access = no_log_pack_access;
+ if (log_pack_access == no_log_pack_access)
+ return;
+
if (!log_file) {
log_file = fopen(log_pack_access, "w");
if (!log_file) {
error("cannot open pack access log '%s' for writing: %s",
log_pack_access, strerror(errno));
- log_pack_access = NULL;
+ log_pack_access = no_log_pack_access;
return;
}
}
@@ -1992,7 +2002,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
int base_from_cache = 0;
- if (log_pack_access)
+ if (log_pack_access != no_log_pack_access)
write_pack_access_log(p, obj_offset);
/* PHASE 1: drill down to the innermost base object */
--
1.8.2.83.gc99314b
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