To be able to add a common prefix or suffix to all trace output (e.g.
a timestamp or file:line of the caller), factor out common setup and
cleanup tasks of the trace* functions.
When adding a common prefix, it makes sense that the output of each trace
call starts on a new line. Add '\n' in case the caller forgot.
Note that this explicitly limits trace output to line-by-line, it is no
longer possible to trace-print just part of a line. Until now, this was
just an implicit assumption (trace-printing part of a line worked, but
messed up the trace file if multiple threads or processes were involved).
Thread-safety / inter-process-safety is also the reason why we need to do
the prefixing and suffixing in memory rather than issuing multiple write()
calls. Write_or_whine_pipe() / xwrite() is atomic unless the size exceeds
MAX_IO_SIZE (8MB, see wrapper.c). In case of trace_strbuf, this costs an
additional string copy (which should be irrelevant for performance in light
of actual file IO).
While we're at it, rename trace_strbuf's 'buf' argument, which suggests
that the function is modifying the buffer. Trace_strbuf() currently is the
only trace API that can print arbitrary binary data (without barfing on
'%' or stopping at '\0'), so 'data' seems more appropriate.
Signed-off-by: Karsten Blees <blees@xxxxxxx>
---
trace.c | 47 +++++++++++++++++++++++++++++++++--------------
trace.h | 2 +-
2 files changed, 34 insertions(+), 15 deletions(-)
diff --git a/trace.c b/trace.c
index 8662b79..3d02bcc 100644
--- a/trace.c
+++ b/trace.c
@@ -85,17 +85,37 @@ void trace_disable(struct trace_key *key)
static const char err_msg[] = "Could not trace into fd given by "
"GIT_TRACE environment variable";
+static int prepare_trace_line(struct trace_key *key, struct strbuf *buf)
+{
+ if (!trace_want(key))
+ return 0;
+
+ set_try_to_free_routine(NULL); /* is never reset */
+
+ /* add line prefix here */
+
+ return 1;
+}
+
+static void print_trace_line(struct trace_key *key, struct strbuf *buf)
+{
+ /* append newline if missing */
+ if (buf->len && buf->buf[buf->len - 1] != '\n')
+ strbuf_addch(buf, '\n');
+
+ write_or_whine_pipe(get_trace_fd(key), buf->buf, buf->len, err_msg);
+ strbuf_release(buf);
+}
+
static void trace_vprintf(struct trace_key *key, const char *format, va_list ap)
{
struct strbuf buf = STRBUF_INIT;
- if (!trace_want(key))
+ if (!prepare_trace_line(key, &buf))
return;
- set_try_to_free_routine(NULL); /* is never reset */
strbuf_vaddf(&buf, format, ap);
- trace_strbuf(key, &buf);
- strbuf_release(&buf);
+ print_trace_line(key, &buf);
}
void trace_printf_key(struct trace_key *key, const char *format, ...)
@@ -114,32 +134,31 @@ void trace_printf(const char *format, ...)
va_end(ap);
}
-void trace_strbuf(struct trace_key *key, const struct strbuf *buf)
+void trace_strbuf(struct trace_key *key, const struct strbuf *data)
{
- int fd = get_trace_fd(key);
- if (!fd)
+ struct strbuf buf = STRBUF_INIT;
+
+ if (!prepare_trace_line(key, &buf))
return;
- write_or_whine_pipe(fd, buf->buf, buf->len, err_msg);
+ strbuf_addbuf(&buf, data);
+ print_trace_line(key, &buf);
}
void trace_argv_printf(const char **argv, const char *format, ...)
{
struct strbuf buf = STRBUF_INIT;
va_list ap;
- int fd = get_trace_fd(NULL);
- if (!fd)
+
+ if (!prepare_trace_line(NULL, &buf))
return;
- set_try_to_free_routine(NULL); /* is never reset */
va_start(ap, format);
strbuf_vaddf(&buf, format, ap);
va_end(ap);
sq_quote_argv(&buf, argv, 0);
- strbuf_addch(&buf, '\n');
- write_or_whine_pipe(fd, buf.buf, buf.len, err_msg);
- strbuf_release(&buf);
+ print_trace_line(NULL, &buf);
}
static const char *quote_crnl(const char *path)
diff --git a/trace.h b/trace.h
index fbfd9f4..e69455f 100644
--- a/trace.h
+++ b/trace.h
@@ -22,6 +22,6 @@ extern int trace_want(struct trace_key *key);
extern void trace_disable(struct trace_key *key);
__attribute__((format (printf, 2, 3)))
extern void trace_printf_key(struct trace_key *key, const char *format, ...);
-extern void trace_strbuf(struct trace_key *key, const struct strbuf *buf);
+extern void trace_strbuf(struct trace_key *key, const struct strbuf *data);
#endif /* TRACE_H */
--
2.0.0.406.ge74f8ff
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