Persistently enabling trace2 output is difficult because it requires
specifying a full filename. This series teaches tr2_dst_get_trace_fd()
to create files underneath a given directory provided as the target of
the GIT_TR2_* envvars.
Changes since V2:
* No longer appends a suffix to filenames on the first creation attempt.
* Renamed function & constant now that randomization is no longer used.
* Simplified strbuf usage.
Changes since V1:
* No longer supports timestamp templates.
* No longer supports filename prefixes.
* Always creates filenames based on the final component of the trace2
SID.
Josh Steadmon (1):
trace2: write to directory targets
Documentation/technical/api-trace2.txt | 5 ++
t/t0210-trace2-normal.sh | 15 ++++++
trace2/tr2_dst.c | 63 +++++++++++++++++++++++++-
3 files changed, 81 insertions(+), 2 deletions(-)
Range-diff against v2:
1: 59d8c6511b ! 1: ce5258610f trace2: write to directory targets
@@ -23,8 +23,8 @@
+ If the target already exists and is a directory, the traces will be
+ written to files (one per process) underneath the given directory. They
-+ will be named according to the last component of the SID followed by a
-+ counter to avoid potential collisions.
++ will be named according to the last component of the SID (optionally
++ followed by a counter to avoid filename collisions).
+
`af_unix:[<socket_type>:]<absolute-pathname>`::
@@ -37,7 +37,7 @@
test_cmp expect actual
'
-+test_expect_success 'randomized filename' '
++test_expect_success 'automatic filename' '
+ test_when_finished "rm -r traces actual expect" &&
+ mkdir traces &&
+ GIT_TR2="$(pwd)/traces" test-tool trace2 001return 0 &&
@@ -71,9 +71,9 @@
#define TR2_ENVVAR_DST_DEBUG "GIT_TR2_DST_DEBUG"
+/*
-+ * How many attempts we will make at creating a random trace output path.
++ * How many attempts we will make at creating an automatically-named trace file.
+ */
-+#define MAX_RANDOM_ATTEMPTS 10
++#define MAX_AUTO_ATTEMPTS 10
+
static int tr2_dst_want_warning(void)
{
@@ -82,45 +82,47 @@
dst->need_close = 0;
}
-+static int tr2_dst_try_random_path(struct tr2_dst *dst, const char *tgt_prefix)
++static int tr2_dst_try_auto_path(struct tr2_dst *dst, const char *tgt_prefix)
+{
+ int fd;
+ const char *last_slash, *sid = tr2_sid_get();
-+ struct strbuf base_path = STRBUF_INIT, final_path = STRBUF_INIT;
++ struct strbuf path = STRBUF_INIT;
++ size_t base_path_len;
+ unsigned attempt_count;
+
+ last_slash = strrchr(sid, '/');
+ if (last_slash)
+ sid = last_slash + 1;
+
-+ strbuf_addstr(&base_path, tgt_prefix);
-+ if (!is_dir_sep(base_path.buf[base_path.len - 1]))
-+ strbuf_addch(&base_path, '/');
-+ strbuf_addstr(&base_path, sid);
++ strbuf_addstr(&path, tgt_prefix);
++ if (!is_dir_sep(path.buf[path.len - 1]))
++ strbuf_addch(&path, '/');
++ strbuf_addstr(&path, sid);
++ base_path_len = path.len;
+
-+ for (attempt_count = 0; attempt_count < MAX_RANDOM_ATTEMPTS; attempt_count++) {
-+ strbuf_reset(&final_path);
-+ strbuf_addbuf(&final_path, &base_path);
-+ strbuf_addf(&final_path, ".%d", attempt_count);
++ for (attempt_count = 0; attempt_count < MAX_AUTO_ATTEMPTS; attempt_count++) {
++ if (attempt_count > 0) {
++ strbuf_setlen(&path, base_path_len);
++ strbuf_addf(&path, ".%d", attempt_count);
++ }
+
-+ fd = open(final_path.buf, O_WRONLY | O_CREAT | O_EXCL, 0666);
++ fd = open(path.buf, O_WRONLY | O_CREAT | O_EXCL, 0666);
+ if (fd != -1)
+ break;
+ }
+
+ if (fd == -1) {
+ if (tr2_dst_want_warning())
-+ warning("trace2: could not open '%s' for '%s' tracing: %s",
-+ base_path.buf, dst->env_var_name, strerror(errno));
++ warning("trace2: could not open '%.*s' for '%s' tracing: %s",
++ (int) base_path_len, path.buf,
++ dst->env_var_name, strerror(errno));
+
+ tr2_dst_trace_disable(dst);
-+ strbuf_release(&base_path);
-+ strbuf_release(&final_path);
++ strbuf_release(&path);
+ return 0;
+ }
+
-+ strbuf_release(&base_path);
-+ strbuf_release(&final_path);
++ strbuf_release(&path);
+
+ dst->fd = fd;
+ dst->need_close = 1;
@@ -140,7 +142,7 @@
- return tr2_dst_try_path(dst, tgt_value);
+ if (is_absolute_path(tgt_value)) {
+ if (is_directory(tgt_value))
-+ return tr2_dst_try_random_path(dst, tgt_value);
++ return tr2_dst_try_auto_path(dst, tgt_value);
+ else
+ return tr2_dst_try_path(dst, tgt_value);
+ }
