[PATCH 20/46] perf tools: Add perf_data_file__switch() helper

Wang Nan
2016-02-26T09:49:02Z

perf_data_file__switch() closes current output file, renames it, then
open a new one to continue record. It will be used by perf record
to split output into multiple perf.data files.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: He Kuang <hekuang@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
tools/perf/util/data.c | 38 ++++++++++++++++++++++++++++++++++++++
tools/perf/util/data.h | 11 ++++++++++-
2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
index 1921942..6840fc9 100644
--- a/tools/perf/util/data.c
+++ b/tools/perf/util/data.c
@@ -136,3 +136,41 @@ ssize_t perf_data_file__write(struct perf_data_file *file,
{
return writen(file->fd, buf, size);
}
+
+int perf_data_file__switch(struct perf_data_file *file,
+ const char *postfix,
+ size_t pos, bool at_exit)
+{
+ char *new_filepath;
+ int ret;
+
+ if (check_pipe(file))
+ return -EINVAL;
+ if (perf_data_file__is_read(file))
+ return -EINVAL;
+
+ if (asprintf(&new_filepath, "%s.%s", file->path, postfix) < 0)
+ return -ENOMEM;
+
+ /* Only fire a warning, don't return error. */
+ if (rename(file->path, new_filepath))
+ pr_warning("Failed to rename %s to %s\n", file->path, new_filepath);
+
+ if (!at_exit) {
+ close(file->fd);
+ ret = perf_data_file__open(file);
+ if (ret < 0)
+ goto out;
+
+ if (lseek(file->fd, pos, SEEK_SET) == (off_t)-1) {
+ ret = -errno;
+ pr_debug("Failed to lseek to %zu: %s",
+ pos, strerror(errno));
+ goto out;
+ }
+ }
+ ret = file->fd;
+out:
+ free(new_filepath);
+ return ret;
+}
diff --git a/tools/perf/util/data.h b/tools/perf/util/data.h
index 2b15d0c..ae510ce 100644
--- a/tools/perf/util/data.h
+++ b/tools/perf/util/data.h
@@ -46,5 +46,14 @@ int perf_data_file__open(struct perf_data_file *file);
void perf_data_file__close(struct perf_data_file *file);
ssize_t perf_data_file__write(struct perf_data_file *file,
void *buf, size_t size);
-
+/*
+ * If at_exit is set, only rename current perf.data to
+ * perf.data.<postfix>, continue write on original file.
+ * Set at_exit when flushing the last output.
+ *
+ * Return value is fd of new output.
+ */
+int perf_data_file__switch(struct perf_data_file *file,
+ const char *postfix,
+ size_t pos, bool at_exit);
#endif /* __PERF_DATA_H */
--
1.8.3.4