From c69dfd24db21be54ec5a17bb3e07c81f4e96861a Mon Sep 17 00:00:00 2001 From: Karsten Blees Date: Sat, 12 Jul 2014 02:02:18 +0200 Subject: [PATCH] trace: add infrastructure to augment trace output with additional info 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 Signed-off-by: Junio C Hamano --- trace.c | 47 +++++++++++++++++++++++++++++++++-------------- trace.h | 2 +- 2 files changed, 34 insertions(+), 15 deletions(-) diff --git a/trace.c b/trace.c index 8662b79801..3d02bcc239 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 d85ac4c652..28c10892df 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 */