[PATCH v6 14/20] perf session: Introduce reader_state in reader object

[Alexey Bayduraev]

We need all the state info about reader in separate object to load data
from multiple files, so we can keep multiple readers at the same time.
Adding struct reader_state and adding all items that need to be kept.

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 | 74 +++++++++++++++++++++++----------------
 1 file changed, 43 insertions(+), 31 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 6ba7da8c5daa..d9ba87a754be 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -55,6 +55,17 @@ typedef s64 (*reader_cb_t)(struct perf_session *session,
 			   u64 file_offset,
 			   const char *file_path);
 
+struct reader_state {
+	char	*mmaps[NUM_MMAPS];
+	size_t	 mmap_size;
+	int	 mmap_idx;
+	char	*mmap_cur;
+	u64	 file_pos;
+	u64	 file_offset;
+	u64	 data_size;
+	u64	 head;
+};
+
 struct reader {
 	int		 fd;
 	const char	 *path;
@@ -62,6 +73,7 @@ struct reader {
 	u64		 data_offset;
 	reader_cb_t	 process;
 	bool		 in_place_update;
+	struct reader_state state;
 };
 
 #ifdef HAVE_ZSTD_SUPPORT
@@ -2175,29 +2187,28 @@ static int
 reader__process_events(struct reader *rd, struct perf_session *session,
 		       struct ui_progress *prog)
 {
-	u64 data_size = rd->data_size;
-	u64 head, page_offset, file_offset, file_pos, size;
-	int err = 0, mmap_prot, mmap_flags, map_idx = 0;
-	size_t	mmap_size;
-	char *buf, *mmaps[NUM_MMAPS];
+	struct reader_state *st = &rd->state;
+	u64 page_offset, size;
+	int err = 0, mmap_prot, mmap_flags;
+	char *buf, **mmaps = st->mmaps;
 	union perf_event *event;
 	s64 skip;
 
 	page_offset = page_size * (rd->data_offset / page_size);
-	file_offset = page_offset;
-	head = rd->data_offset - page_offset;
+	st->file_offset = page_offset;
+	st->head = rd->data_offset - page_offset;
 
-	ui_progress__init_size(prog, data_size, "Processing events...");
+	ui_progress__init_size(prog, rd->data_size, "Processing events...");
 
-	data_size += rd->data_offset;
+	st->data_size = rd->data_size + rd->data_offset;
 
-	mmap_size = MMAP_SIZE;
-	if (mmap_size > data_size) {
-		mmap_size = data_size;
+	st->mmap_size = MMAP_SIZE;
+	if (st->mmap_size > st->data_size) {
+		st->mmap_size = st->data_size;
 		session->one_mmap = true;
 	}
 
-	memset(mmaps, 0, sizeof(mmaps));
+	memset(mmaps, 0, sizeof(st->mmaps));
 
 	mmap_prot  = PROT_READ;
 	mmap_flags = MAP_SHARED;
@@ -2209,35 +2220,36 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 		mmap_flags = MAP_PRIVATE;
 	}
 remap:
-	buf = mmap(NULL, mmap_size, mmap_prot, mmap_flags, rd->fd,
-		   file_offset);
+	buf = mmap(NULL, st->mmap_size, mmap_prot, mmap_flags, rd->fd,
+		   st->file_offset);
 	if (buf == MAP_FAILED) {
 		pr_err("failed to mmap file\n");
 		err = -errno;
 		goto out;
 	}
-	mmaps[map_idx] = buf;
-	map_idx = (map_idx + 1) & (ARRAY_SIZE(mmaps) - 1);
-	file_pos = file_offset + head;
+	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;
 	if (session->one_mmap) {
 		session->one_mmap_addr = buf;
-		session->one_mmap_offset = file_offset;
+		session->one_mmap_offset = st->file_offset;
 	}
 
 more:
-	event = fetch_mmaped_event(head, mmap_size, buf, session->header.needs_swap);
+	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) {
-		if (mmaps[map_idx]) {
-			munmap(mmaps[map_idx], mmap_size);
-			mmaps[map_idx] = NULL;
+		if (mmaps[st->mmap_idx]) {
+			munmap(mmaps[st->mmap_idx], st->mmap_size);
+			mmaps[st->mmap_idx] = NULL;
 		}
 
-		page_offset = page_size * (head / page_size);
-		file_offset += page_offset;
-		head -= page_offset;
+		page_offset = page_size * (st->head / page_size);
+		st->file_offset += page_offset;
+		st->head -= page_offset;
 		goto remap;
 	}
 
@@ -2246,9 +2258,9 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 	skip = -EINVAL;
 
 	if (size < sizeof(struct perf_event_header) ||
-	    (skip = rd->process(session, event, file_pos, rd->path)) < 0) {
+	    (skip = rd->process(session, event, st->file_pos, rd->path)) < 0) {
 		pr_err("%#" PRIx64 " [%s] [%#x]: failed to process type: %d [%s]\n",
-		       file_offset + head, rd->path, event->header.size,
+		       st->file_offset + st->head, rd->path, event->header.size,
 		       event->header.type, strerror(-skip));
 		err = skip;
 		goto out;
@@ -2257,8 +2269,8 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 	if (skip)
 		size += skip;
 
-	head += size;
-	file_pos += size;
+	st->head += size;
+	st->file_pos += size;
 
 	err = __perf_session__process_decomp_events(session);
 	if (err)
@@ -2269,7 +2281,7 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 	if (session_done())
 		goto out;
 
-	if (file_pos < data_size)
+	if (st->file_pos < st->data_size)
 		goto more;
 
 out:
-- 
2.19.0