When the value of a trace2 environment variable is an absolute path
referring to an existing directory, write output to files (one per
process) underneath the given directory. Files will be named according
to the final component of the trace2 SID, followed by a counter to avoid
potential collisions.
This makes it more convenient to collect traces for every git invocation
by unconditionally setting the relevant trace2 envvar to a constant
directory name.
Signed-off-by: Josh Steadmon <steadmon@xxxxxxxxxx>
---
Documentation/technical/api-trace2.txt | 5 +++
t/t0210-trace2-normal.sh | 15 +++++++
trace2/tr2_dst.c | 61 +++++++++++++++++++++++++-
3 files changed, 79 insertions(+), 2 deletions(-)
diff --git a/Documentation/technical/api-trace2.txt b/Documentation/technical/api-trace2.txt
index 2de565fa3d..318673e8e5 100644
--- a/Documentation/technical/api-trace2.txt
+++ b/Documentation/technical/api-trace2.txt
@@ -109,6 +109,11 @@ values are recognized.
Enables the target, opens and writes to the file in append mode.
+ 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.
+
`af_unix:[<socket_type>:]<absolute-pathname>`::
Enables the target, opens and writes to a Unix Domain Socket
diff --git a/t/t0210-trace2-normal.sh b/t/t0210-trace2-normal.sh
index 03a0aedb1d..26c9c1b3b8 100755
--- a/t/t0210-trace2-normal.sh
+++ b/t/t0210-trace2-normal.sh
@@ -80,6 +80,21 @@ test_expect_success 'normal stream, return code 1' '
test_cmp expect actual
'
+test_expect_success 'randomized filename' '
+ test_when_finished "rm -r traces actual expect" &&
+ mkdir traces &&
+ GIT_TR2="$(pwd)/traces" test-tool trace2 001return 0 &&
+ perl "$TEST_DIRECTORY/t0210/scrub_normal.perl" <"$(ls traces/*)" >actual &&
+ cat >expect <<-EOF &&
+ version $V
+ start _EXE_ trace2 001return 0
+ cmd_name trace2 (trace2)
+ exit elapsed:_TIME_ code:0
+ atexit elapsed:_TIME_ code:0
+ EOF
+ test_cmp expect actual
+'
+
# Verb 002exit
#
# Explicit exit(code) from within cmd_<verb> propagates <code>.
diff --git a/trace2/tr2_dst.c b/trace2/tr2_dst.c
index fd490a43ad..0e752914dc 100644
--- a/trace2/tr2_dst.c
+++ b/trace2/tr2_dst.c
@@ -1,5 +1,6 @@
#include "cache.h"
#include "trace2/tr2_dst.h"
+#include "trace2/tr2_sid.h"
/*
* If a Trace2 target cannot be opened for writing, we should issue a
@@ -12,6 +13,11 @@
*/
#define TR2_ENVVAR_DST_DEBUG "GIT_TR2_DST_DEBUG"
+/*
+ * How many attempts we will make at creating a random trace output path.
+ */
+#define MAX_RANDOM_ATTEMPTS 10
+
static int tr2_dst_want_warning(void)
{
static int tr2env_dst_debug = -1;
@@ -36,6 +42,53 @@ void tr2_dst_trace_disable(struct tr2_dst *dst)
dst->need_close = 0;
}
+static int tr2_dst_try_random_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;
+ 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);
+
+ 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);
+
+ fd = open(final_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));
+
+ tr2_dst_trace_disable(dst);
+ strbuf_release(&base_path);
+ strbuf_release(&final_path);
+ return 0;
+ }
+
+ strbuf_release(&base_path);
+ strbuf_release(&final_path);
+
+ dst->fd = fd;
+ dst->need_close = 1;
+ dst->initialized = 1;
+
+ return dst->fd;
+}
+
static int tr2_dst_try_path(struct tr2_dst *dst, const char *tgt_value)
{
int fd = open(tgt_value, O_WRONLY | O_APPEND | O_CREAT, 0666);
@@ -202,8 +255,12 @@ int tr2_dst_get_trace_fd(struct tr2_dst *dst)
return dst->fd;
}
- if (is_absolute_path(tgt_value))
- 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);
+ else
+ return tr2_dst_try_path(dst, tgt_value);
+ }
#ifndef NO_UNIX_SOCKETS
if (starts_with(tgt_value, PREFIX_AF_UNIX))
--
2.21.0.225.g810b269d1ac-goog
