core: use env variable instead of config var to turn on logging pack access
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@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Nguyễn Thái Ngọc Duy committed
Jun 9, 2013 at 12:22 UTC
b12ca9631f86adc35b0c03fb5b792cd82c288288
5 files changed
+19
-9
Documentation/git.txt
+7
@@ -832,6 +832,13 @@ for further details.
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as a file path and will try to write the trace messages
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into it.
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+'GIT_TRACE_PACK_ACCESS'::
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+ If this variable is set to a path, a file will be created at
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+ the given path logging all accesses to any packs. For each
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+ access, the pack file name and an offset in the pack is
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+ recorded. This may be helpful for troubleshooting some
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+ pack-related performance problems.
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+
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GIT_LITERAL_PATHSPECS::
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Setting this variable to `1` will cause Git to treat all
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pathspecs literally, rather than as glob patterns. For example,
cache.h
-3
@@ -772,9 +772,6 @@ extern int parse_sha1_header(const char *hdr, unsigned long *sizep);
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/* global flag to enable extra checks when accessing packed objects */
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extern int do_check_packed_object_crc;
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-/* for development: log offset of pack access */
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-extern const char *log_pack_access;
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-
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extern int check_sha1_signature(const unsigned char *sha1, void *buf, unsigned long size, const char *type);
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extern int move_temp_to_file(const char *tmpfile, const char *filename);
config.c
-3
@@ -675,9 +675,6 @@ static int git_default_core_config(const char *var, const char *value)
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return 0;
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}
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- if (!strcmp(var, "core.logpackaccess"))
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- return git_config_string(&log_pack_access, var, value);
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-
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if (!strcmp(var, "core.autocrlf")) {
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if (value && !strcasecmp(value, "input")) {
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if (core_eol == EOL_CRLF)
environment.c
-1
@@ -37,7 +37,6 @@ size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
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size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
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size_t delta_base_cache_limit = 16 * 1024 * 1024;
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unsigned long big_file_threshold = 512 * 1024 * 1024;
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-const char *log_pack_access;
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const char *pager_program;
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int pager_use_color = 1;
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const char *editor_program;
sha1_file.c
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-2
@@ -36,6 +36,9 @@ static inline uintmax_t sz_fmt(size_t s) { return s; }
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const unsigned char null_sha1[20];
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+static const char *no_log_pack_access = "no_log_pack_access";
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+static const char *log_pack_access;
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+
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/*
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* This is meant to hold a *small* number of objects that you would
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* 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)
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{
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static FILE *log_file;
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+ if (!log_pack_access)
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+ log_pack_access = getenv("GIT_TRACE_PACK_ACCESS");
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+ if (!log_pack_access)
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+ log_pack_access = no_log_pack_access;
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+ if (log_pack_access == no_log_pack_access)
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+ return;
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+
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if (!log_file) {
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log_file = fopen(log_pack_access, "w");
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if (!log_file) {
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error("cannot open pack access log '%s' for writing: %s",
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log_pack_access, strerror(errno));
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- log_pack_access = NULL;
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+ log_pack_access = no_log_pack_access;
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return;
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}
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}
@@ -1992,7 +2002,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
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int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
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int base_from_cache = 0;
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- if (log_pack_access)
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+ if (log_pack_access != no_log_pack_access)
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write_pack_access_log(p, obj_offset);
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/* PHASE 1: drill down to the innermost base object */