[PATCH v5 19/20] perf session: load single file for analysis

[Alexey Bayduraev]

Adding eof flag to reader state and moving the check to reader__mmap.
Separating reading code of single event into reader__read_event function.
Adding basic reader return codes to simplify the code and introducing
reader remmap/read_event loop based on them.

Design and implementation are based on the prototype [1], [2].

[1] git clone https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git -b perf/record_threads
[2] https://lore.kernel.org/lkml/20180913125450.21342-1-jolsa@xxxxxxxxxx/

Suggested-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@xxxxxxxxxxxxxxx>
---
 tools/perf/util/session.c | 71 ++++++++++++++++++++++++---------------
 1 file changed, 44 insertions(+), 27 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 5bb3babeeb94..47a414016510 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -64,6 +64,12 @@ struct reader_state {
 	u64	 file_offset;
 	u64	 data_size;
 	u64	 head;
+	bool	 eof;
+};
+
+enum {
+	READER_EOF	=  0,
+	READER_OK	=  1,
 };
 
 struct reader {
@@ -2241,6 +2247,11 @@ reader__mmap(struct reader *rd, struct perf_session *session)
 	char *buf, **mmaps = st->mmaps;
 	u64 page_offset;
 
+	if (st->file_pos >= st->data_size) {
+		st->eof = true;
+		return READER_EOF;
+	}
+
 	mmap_prot  = PROT_READ;
 	mmap_flags = MAP_SHARED;
 
@@ -2267,36 +2278,26 @@ reader__mmap(struct reader *rd, struct perf_session *session)
 	mmaps[st->mmap_idx] = st->mmap_cur = buf;
 	st->mmap_idx = (st->mmap_idx + 1) & (ARRAY_SIZE(st->mmaps) - 1);
 	st->file_pos = st->file_offset + st->head;
-	return 0;
+	return READER_OK;
 }
 
 static int
-reader__process_events(struct reader *rd, struct perf_session *session,
-		       struct ui_progress *prog)
+reader__read_event(struct reader *rd, struct perf_session *session,
+		   struct ui_progress *prog)
 {
 	struct reader_state *st = &rd->state;
-	u64 size;
-	int err = 0;
+	int err = READER_OK;
 	union perf_event *event;
+	u64 size;
 	s64 skip;
 
-remap:
-	err = reader__mmap(rd, session);
-	if (err)
-		goto out;
-	if (session->one_mmap) {
-		session->one_mmap_addr   = rd->state.mmap_cur;
-		session->one_mmap_offset = rd->state.file_offset;
-	}
-
-more:
 	event = fetch_mmaped_event(st->head, st->mmap_size, st->mmap_cur,
 				   session->header.needs_swap);
 	if (IS_ERR(event))
 		return PTR_ERR(event);
 
 	if (!event)
-		goto remap;
+		return READER_EOF;
 
 	session->active_reader = rd;
 	size = event->header.size;
@@ -2318,18 +2319,12 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 	st->head += size;
 	st->file_pos += size;
 
-	err = __perf_session__process_decomp_events(session);
-	if (err)
-		goto out;
+	skip = __perf_session__process_decomp_events(session);
+	if (skip)
+		err = skip;
 
 	ui_progress__update(prog, size);
 
-	if (session_done())
-		goto out;
-
-	if (st->file_pos < st->data_size)
-		goto more;
-
 out:
 	session->active_reader = NULL;
 	return err;
@@ -2372,9 +2367,31 @@ static int __perf_session__process_events(struct perf_session *session)
 	err = reader__init(rd, &session->one_mmap);
 	if (err)
 		goto out_err;
-	err = reader__process_events(rd, session, &prog);
-	if (err)
+	err = reader__mmap(rd, session);
+	if (err != READER_OK) {
+		if (err == READER_EOF)
+			err = -EINVAL;
 		goto out_err;
+	}
+	if (session->one_mmap) {
+		session->one_mmap_addr   = rd->state.mmap_cur;
+		session->one_mmap_offset = rd->state.file_offset;
+	}
+
+	while (true) {
+		if (session_done())
+			break;
+
+		err = reader__read_event(rd, session, &prog);
+		if (err < 0)
+			break;
+		if (err == READER_EOF) {
+			err = reader__mmap(rd, session);
+			if (err <= 0)
+				break;
+		}
+	}
+
 	/* do the final flush for ordered samples */
 	err = ordered_events__flush(oe, OE_FLUSH__FINAL);
 	if (err)
-- 
2.19.0