perf data: Add perf_data_file__switch() helper

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

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1460535673-159866-3-git-send-email-wangnan0@huawei.com
Signed-off-by: He Kuang <hekuang@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 51 insertions, 1 deletions

diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
index 1921942fc2e0..be83516155ee 100644
--- a/tools/perf/util/data.c
+++ b/tools/perf/util/data.c
@@ -136,3 +136,44 @@ 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, continue fill
+         * original file.
+         */
+        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 2b15d0c95c7f..ae510ce16cb1 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 */