Changes since V4:
* Avoid the use of the non-specific term "overload" in code, trace
output, commit messages, and documentation.
* Remove an unnecessary <dirent.h> include that was breaking the Windows
build.
Josh Steadmon (4):
docs: mention trace2 target-dir mode in git-config
docs: clarify trace2 version invariants
trace2: discard new traces if target directory has too many files
trace2: write discard message to sentinel files
Documentation/config/trace2.txt | 6 ++
Documentation/technical/api-trace2.txt | 31 +++++--
Documentation/trace2-target-values.txt | 4 +-
t/t0212-trace2-event.sh | 19 +++++
trace2/tr2_dst.c | 111 ++++++++++++++++++++++---
trace2/tr2_dst.h | 1 +
trace2/tr2_sysenv.c | 3 +
trace2/tr2_sysenv.h | 2 +
trace2/tr2_tgt_event.c | 31 +++++--
trace2/tr2_tgt_normal.c | 2 +-
trace2/tr2_tgt_perf.c | 2 +-
11 files changed, 184 insertions(+), 28 deletions(-)
Range-diff against v4:
1: 98a8440d3f ! 1: 391051b308 trace2: don't overload target directories
@@ Metadata
Author: Josh Steadmon <stead...@google.com>
## Commit message ##
- trace2: don't overload target directories
+ trace2: discard new traces if target directory has too many files
trace2 can write files into a target directory. With heavy usage, this
directory can fill up with files, causing difficulty for
@@ Commit message
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 directory is overloaded. A directory is overloaded
- if there is a sentinel file declaring an overload, or if the number
of
- files exceeds trace2.maxFiles. If the latter, create a sentinel file
- to speed up later overload checks.
+ 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
- overload check.
+ 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.
@@ t/t0212-trace2-event.sh: test_expect_success JSON_PP 'using global
config, event
test_cmp expect actual
'
-+test_expect_success "don't overload target directory" '
++test_expect_success 'discard traces when there are too many files' '
+ mkdir trace_target_dir &&
+ test_when_finished "rm -r trace_target_dir" &&
+ (
@@ t/t0212-trace2-event.sh: test_expect_success JSON_PP 'using global
config, event
+ cd .. &&
+ GIT_TRACE2_EVENT="$(pwd)/trace_target_dir" test-tool trace2
001return 0
+ ) &&
-+ echo git-trace2-overload >>expected_filenames.txt &&
++ echo git-trace2-discard >>expected_filenames.txt &&
+ ls trace_target_dir >ls_output.txt &&
+ test_cmp expected_filenames.txt ls_output.txt
+'
@@ t/t0212-trace2-event.sh: test_expect_success JSON_PP 'using global
config, event
test_done
## trace2/tr2_dst.c ##
-@@
-+#include <dirent.h>
-+
- #include "cache.h"
- #include "trace2/tr2_dst.h"
- #include "trace2/tr2_sid.h"
@@
*/
#define MAX_AUTO_ATTEMPTS 10
+/*
-+ * Sentinel file used to detect when we're overloading a directory with
too many
-+ * trace files.
++ * Sentinel file used to detect when we should discard new traces to avoid
++ * writing too many trace files to a directory.
+ */
-+#define OVERLOAD_SENTINEL_NAME "git-trace2-overload"
++#define DISCARD_SENTINEL_NAME "git-trace2-discard"
+
+/*
-+ * When set to zero, disables directory overload checking. Otherwise,
controls
-+ * how many files we can write to a directory before entering overload
mode.
++ * When set to zero, disables directory file count checks. Otherwise,
controls
++ * how many files we can write to a directory before entering discard
mode.
+ * This can be overridden via the TR2_SYSENV_MAX_FILES setting.
+ */
+static int tr2env_max_files = 0;
@@ trace2/tr2_dst.c: void tr2_dst_trace_disable(struct tr2_dst *dst)
+ * from the target directory; after it removes the sentinel file we'll
start
+ * writing traces again.
+ */
-+static int tr2_dst_overloaded(const char *tgt_prefix)
++static int tr2_dst_too_many_files(const char *tgt_prefix)
+{
+ int file_count = 0, max_files = 0, ret = 0;
+ const char *max_files_var;
@@ trace2/tr2_dst.c: void tr2_dst_trace_disable(struct tr2_dst *dst)
+
+ /* check sentinel */
+ strbuf_addbuf(&sentinel_path, &path);
-+ strbuf_addstr(&sentinel_path, OVERLOAD_SENTINEL_NAME);
++ strbuf_addstr(&sentinel_path, DISCARD_SENTINEL_NAME);
+ if (!stat(sentinel_path.buf, &statbuf)) {
+ ret = 1;
+ goto cleanup;
@@ trace2/tr2_dst.c: static int tr2_dst_try_auto_path(struct tr2_dst *dst,
const ch
strbuf_addstr(&path, sid);
base_path_len = path.len;
-+ if (tr2_dst_overloaded(tgt_prefix)) {
++ if (tr2_dst_too_many_files(tgt_prefix)) {
+ strbuf_release(&path);
+ if (tr2_dst_want_warning())
+ warning("trace2: not opening %s trace file due to too "
2: 790c5ac95a ! 2: 1c3c7f01c6 trace2: write overload message to sentinel files
@@ Metadata
Author: Josh Steadmon <stead...@google.com>
## Commit message ##
- trace2: write overload message to sentinel files
+ trace2: write discard message to sentinel files
- Add a new "overload" event type for trace2 event destinations. When the
- trace2 overload feature creates a sentinel file, it will include the
- normal trace2 output in the sentinel, along with this new overload
+ Add a new "discard" event type for trace2 event destinations. When the
+ trace2 file count check creates a sentinel file, it will include the
+ normal trace2 output in the sentinel, along with this new discard
event.
Writing this message into the sentinel file is useful for tracking how
- often the overload protection feature is triggered in practice.
+ often the file count check triggers in practice.
Bump up the event format version since we've added a new event type.
@@ Documentation/technical/api-trace2.txt: only present on the "start" and
"atexit"
}
------------
-+`"overload"`::
-+ This event is created in a sentinel file if we are overloading a target
-+ trace directory (see the trace2.maxFiles config option).
++`"discard"`::
++ This event is written to the git-trace2-discard sentinel file if there
++ are too many files in the target trace directory (see the
++ trace2.maxFiles config option).
++
+------------
+{
-+ "event":"overload",
++ "event":"discard",
+ ...
+}
+------------
@@ Documentation/technical/api-trace2.txt: only present on the "start" and
"atexit"
+
## t/t0212-trace2-event.sh ##
-@@ t/t0212-trace2-event.sh: test_expect_success "don't overload target
directory" '
+@@ t/t0212-trace2-event.sh: test_expect_success 'discard traces when there
are too many files' '
) &&
- echo git-trace2-overload >>expected_filenames.txt &&
+ echo git-trace2-discard >>expected_filenames.txt &&
ls trace_target_dir >ls_output.txt &&
- test_cmp expected_filenames.txt ls_output.txt
+ test_cmp expected_filenames.txt ls_output.txt &&
-+ head -n1 trace_target_dir/git-trace2-overload | grep
\"event\":\"version\" &&
-+ head -n2 trace_target_dir/git-trace2-overload | tail -n1 | grep
\"event\":\"overload\"
++ head -n1 trace_target_dir/git-trace2-discard | grep
\"event\":\"version\" &&
++ head -n2 trace_target_dir/git-trace2-discard | tail -n1 | grep
\"event\":\"too_many_files\"
'
test_done
@@ trace2/tr2_dst.c: void tr2_dst_trace_disable(struct tr2_dst *dst)
+ * sentinel file, then check file count.
+ *
+ * Returns 0 if tracing should proceed as normal. Returns 1 if the
sentinel file
-+ * already exists, which means tracing should be disabled. Returns -1 if
we are
-+ * overloaded but there was no sentinel file, which means we have created
and
-+ * should write traces to the sentinel file.
++ * already exists, which means tracing should be disabled. Returns -1 if
there
++ * are too many files but there was no sentinel file, which means we have
++ * created and should write traces to the sentinel file.
*
* We expect that some trace processing system is gradually collecting
files
* from the target directory; after it removes the sentinel file we'll
start
* writing traces again.
*/
--static int tr2_dst_overloaded(const char *tgt_prefix)
-+static int tr2_dst_overloaded(struct tr2_dst *dst, const char *tgt_prefix)
+-static int tr2_dst_too_many_files(const char *tgt_prefix)
++static int tr2_dst_too_many_files(struct tr2_dst *dst, const char
*tgt_prefix)
{
int file_count = 0, max_files = 0, ret = 0;
const char *max_files_var;
-@@ trace2/tr2_dst.c: static int tr2_dst_overloaded(const char *tgt_prefix)
+@@ trace2/tr2_dst.c: static int tr2_dst_too_many_files(const char
*tgt_prefix)
closedir(dirp);
if (file_count >= tr2env_max_files) {
- creat(sentinel_path.buf, 0666);
- ret = 1;
-+ dst->overloaded = 1;
++ dst->too_many_files = 1;
+ dst->fd = open(sentinel_path.buf, O_WRONLY | O_CREAT | O_EXCL,
0666);
+ ret = -1;
goto cleanup;
}
-@@ trace2/tr2_dst.c: static int tr2_dst_overloaded(const char *tgt_prefix)
+@@ trace2/tr2_dst.c: static int tr2_dst_too_many_files(const char
*tgt_prefix)
static int tr2_dst_try_auto_path(struct tr2_dst *dst, const char
*tgt_prefix)
{
- int fd;
-+ int overloaded;
++ int too_many_files;
const char *last_slash, *sid = tr2_sid_get();
struct strbuf path = STRBUF_INIT;
size_t base_path_len;
@@ trace2/tr2_dst.c: static int tr2_dst_try_auto_path(struct tr2_dst *dst,
const ch
strbuf_addstr(&path, sid);
base_path_len = path.len;
-- if (tr2_dst_overloaded(tgt_prefix)) {
-+ overloaded = tr2_dst_overloaded(dst, tgt_prefix);
-+ if (!overloaded) {
+- if (tr2_dst_too_many_files(tgt_prefix)) {
++ too_many_files = tr2_dst_too_many_files(dst, tgt_prefix);
++ if (!too_many_files) {
+ for (attempt_count = 0; attempt_count < MAX_AUTO_ATTEMPTS;
attempt_count++) {
+ if (attempt_count > 0) {
+ strbuf_setlen(&path, base_path_len);
@@ trace2/tr2_dst.c: static int tr2_dst_try_auto_path(struct tr2_dst *dst,
const ch
+ if (dst->fd != -1)
+ break;
+ }
-+ } else if (overloaded == 1) {
++ } else if (too_many_files == 1) {
strbuf_release(&path);
if (tr2_dst_want_warning())
warning("trace2: not opening %s trace file due to too "
@@ trace2/tr2_dst.h: struct tr2_dst {
int fd;
unsigned int initialized : 1;
unsigned int need_close : 1;
-+ unsigned int overloaded : 1;
++ unsigned int too_many_files : 1;
};
/*
@@ trace2/tr2_tgt_event.c: static void event_fmt_prepare(const char
*event_name, co
jw_object_intmax(jw, "repo", repo->trace2_repo_id);
}
-+static void fn_overload_fl(const char *file, int line)
++static void fn_too_many_files_fl(const char *file, int line)
+{
-+ const char *event_name = "overload";
++ const char *event_name = "too_many_files";
+ struct json_writer jw = JSON_WRITER_INIT;
+
+ jw_object_begin(&jw, 0);
@@ trace2/tr2_tgt_event.c: static void fn_version_fl(const char *file, int
line)
tr2_dst_write_line(&tr2dst_event, &jw.json);
jw_release(&jw);
+
-+ if (tr2dst_event.overloaded)
-+ fn_overload_fl(file, line);
++ if (tr2dst_event.too_many_files)
++ fn_too_many_files_fl(file, line);
}
static void fn_start_fl(const char *file, int line,
--
2.23.0.581.g78d2f28ef7-goog
