83e57b04e6
trace2 can write files into a target directory. With heavy usage, this
directory can fill up with files, causing difficulty for
trace-processing systems.
This patch adds a config option (trace2.maxFiles) to set a maximum
number of files that trace2 will write to a target directory. The
following behavior is enabled when the maxFiles is set to a positive
integer:
When trace2 would write a file to a target directory, first check
whether or not the traces should be discarded. Traces should be
discarded if:
* there is a sentinel file declaring that there are too many files
* OR, the number of files exceeds trace2.maxFiles.
In the latter case, we create a sentinel file named git-trace2-discard
to speed up future checks.
The assumption is that a separate trace-processing system is dealing
with the generated traces; once it processes and removes the sentinel
file, it should be safe to generate new trace files again.
The default value for trace2.maxFiles is zero, which disables the file
count check.
The config can also be overridden with a new environment variable:
GIT_TRACE2_MAX_FILES.
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
131 lines
3.6 KiB
C
131 lines
3.6 KiB
C
#include "cache.h"
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#include "config.h"
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#include "dir.h"
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#include "tr2_sysenv.h"
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/*
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* Each entry represents a trace2 setting.
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* See Documentation/technical/api-trace2.txt
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*/
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struct tr2_sysenv_entry {
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const char *env_var_name;
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const char *git_config_name;
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char *value;
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unsigned int getenv_called : 1;
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};
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/*
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* This table must match "enum tr2_sysenv_variable" in tr2_sysenv.h.
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*
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* The strings in this table are constant and must match the published
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* config and environment variable names as described in the documentation.
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*
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* We do not define entries for the GIT_TRACE2_PARENT_* environment
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* variables because they are transient and used to pass information
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* from parent to child git processes, rather than settings.
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*/
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/* clang-format off */
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static struct tr2_sysenv_entry tr2_sysenv_settings[] = {
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[TR2_SYSENV_CFG_PARAM] = { "GIT_TRACE2_CONFIG_PARAMS",
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"trace2.configparams" },
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[TR2_SYSENV_DST_DEBUG] = { "GIT_TRACE2_DST_DEBUG",
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"trace2.destinationdebug" },
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[TR2_SYSENV_NORMAL] = { "GIT_TRACE2",
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"trace2.normaltarget" },
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[TR2_SYSENV_NORMAL_BRIEF] = { "GIT_TRACE2_BRIEF",
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"trace2.normalbrief" },
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[TR2_SYSENV_EVENT] = { "GIT_TRACE2_EVENT",
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"trace2.eventtarget" },
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[TR2_SYSENV_EVENT_BRIEF] = { "GIT_TRACE2_EVENT_BRIEF",
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"trace2.eventbrief" },
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[TR2_SYSENV_EVENT_NESTING] = { "GIT_TRACE2_EVENT_NESTING",
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"trace2.eventnesting" },
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[TR2_SYSENV_PERF] = { "GIT_TRACE2_PERF",
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"trace2.perftarget" },
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[TR2_SYSENV_PERF_BRIEF] = { "GIT_TRACE2_PERF_BRIEF",
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"trace2.perfbrief" },
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[TR2_SYSENV_MAX_FILES] = { "GIT_TRACE2_MAX_FILES",
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"trace2.maxfiles" },
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};
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/* clang-format on */
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static int tr2_sysenv_cb(const char *key, const char *value, void *d)
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{
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int k;
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if (!starts_with(key, "trace2."))
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return 0;
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for (k = 0; k < ARRAY_SIZE(tr2_sysenv_settings); k++) {
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if (!strcmp(key, tr2_sysenv_settings[k].git_config_name)) {
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free(tr2_sysenv_settings[k].value);
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tr2_sysenv_settings[k].value = xstrdup(value);
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return 0;
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}
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}
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return 0;
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}
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/*
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* Load Trace2 settings from the system config (usually "/etc/gitconfig"
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* unless we were built with a runtime-prefix). These are intended to
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* define the default values for Trace2 as requested by the administrator.
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*
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* Then override with the Trace2 settings from the global config.
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*/
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void tr2_sysenv_load(void)
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{
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if (ARRAY_SIZE(tr2_sysenv_settings) != TR2_SYSENV_MUST_BE_LAST)
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BUG("tr2_sysenv_settings size is wrong");
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read_very_early_config(tr2_sysenv_cb, NULL);
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}
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/*
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* Return the value for the requested Trace2 setting from these sources:
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* the system config, the global config, and the environment.
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*/
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const char *tr2_sysenv_get(enum tr2_sysenv_variable var)
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{
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if (var >= TR2_SYSENV_MUST_BE_LAST)
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BUG("tr2_sysenv_get invalid var '%d'", var);
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if (!tr2_sysenv_settings[var].getenv_called) {
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const char *v = getenv(tr2_sysenv_settings[var].env_var_name);
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if (v && *v) {
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free(tr2_sysenv_settings[var].value);
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tr2_sysenv_settings[var].value = xstrdup(v);
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}
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tr2_sysenv_settings[var].getenv_called = 1;
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}
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return tr2_sysenv_settings[var].value;
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}
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/*
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* Return a friendly name for this setting that is suitable for printing
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* in an error messages.
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*/
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const char *tr2_sysenv_display_name(enum tr2_sysenv_variable var)
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{
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if (var >= TR2_SYSENV_MUST_BE_LAST)
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BUG("tr2_sysenv_get invalid var '%d'", var);
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return tr2_sysenv_settings[var].env_var_name;
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}
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void tr2_sysenv_release(void)
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{
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int k;
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for (k = 0; k < ARRAY_SIZE(tr2_sysenv_settings); k++)
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free(tr2_sysenv_settings[k].value);
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}
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