improvement1:
Current code makes more readable messages to vanish as pull_len = len
|------- pull_len = len ----------|
|----------< len >-----------------| ^ new r_off
^old w_off ^r_off ^new w_off
New version reduces the total skipped readable messages
|- pull_len = (len - (r_off - old_w_off)) + 1 --|
|----------< len >-----------------|
^ new r_off
^old w_off ^r_off ^new w_off
improvement2:
If we have fixed one r_off the same fix can be applied to all other
offsets
Signed-off-by: Arun chandran <[email protected]>
---
drivers/staging/android/logger.c | 37
+++++++++++++++++++++++++++++++++----
1 file changed, 33 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/android/logger.c
b/drivers/staging/android/logger.c
index eb3d4ca..2c5d882 100644
--- a/drivers/staging/android/logger.c
+++ b/drivers/staging/android/logger.c
@@ -366,6 +366,24 @@ static inline int is_between(size_t a, size_t b,
size_t c)
}
/*
+ * find_pull_len - calculate how much we need to pull lapped readers
+ *
+ * Caller must hold log->mutex.
+ */
+static size_t find_pull_len(struct logger_log *log, size_t from, size_t
len)
+{
+ size_t skip_len;
+
+ if (from > log->w_off)
+ skip_len = from - log->w_off;
+ else
+ skip_len = log->size - (log->w_off - from);
+
+ /* +1 so that w_off and r_off don't collide */
+ return (len - skip_len) + 1;
+}
+
+/*
* fix_up_readers - walk the list of all readers and "fix up" any who were
* lapped by the writer; also do the same for the default "start head".
* We do this by "pulling forward" the readers and start head to the first
@@ -377,14 +395,25 @@ static void fix_up_readers(struct logger_log *log,
size_t len)
{
size_t old = log->w_off;
size_t new = logger_offset(log, old + len);
+ size_t pull, fix = 0;
struct logger_reader *reader;
- if (is_between(old, new, log->head))
- log->head = get_next_entry(log, log->head, len);
+ if (is_between(old, new, log->head)) {
+ pull = find_pull_len(log, log->head, len);
+ fix = get_next_entry(log, log->head, pull);
+ log->head = fix;
+ }
list_for_each_entry(reader, &log->readers, list)
- if (is_between(old, new, reader->r_off))
- reader->r_off = get_next_entry(log, reader->r_off, len);
+ if (is_between(old, new, reader->r_off)) {
+ if (fix) {
+ reader->r_off = fix;
+ } else {
+ pull = find_pull_len(log, reader->r_off, len);
+ fix = get_next_entry(log, reader->r_off, pull);
+ reader->r_off = fix;
+ }
+ }
}
/*
--
1.7.9.5
--
--
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>From 5abbb49c981fd928c7ae8b4b2d4fdd685c9868fb Mon Sep 17 00:00:00 2001
From: Arun chandran <[email protected]>
Date: Sun, 7 Apr 2013 15:08:00 +0530
Subject: [PATCH] Android logger:improve fix_up_readers()
improvement1:
Current code makes more readable messages to vanish as pull_len = len
|------- pull_len = len ----------|
|----------< len >-----------------| ^ new r_off
^old w_off ^r_off ^new w_off
New version reduces the total skipped readable messages
|- pull_len = (len - (r_off - old_w_off)) + 1 --|
|----------< len >-----------------| ^ new r_off
^old w_off ^r_off ^new w_off
improvement2:
If we have fixed one r_off the same fix can be applied to all other
offsets
Signed-off-by: Arun chandran <[email protected]>
---
drivers/staging/android/logger.c | 37 +++++++++++++++++++++++++++++++++----
1 file changed, 33 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c
index eb3d4ca..2c5d882 100644
--- a/drivers/staging/android/logger.c
+++ b/drivers/staging/android/logger.c
@@ -366,6 +366,24 @@ static inline int is_between(size_t a, size_t b, size_t c)
}
/*
+ * find_pull_len - calculate how much we need to pull lapped readers
+ *
+ * Caller must hold log->mutex.
+ */
+static size_t find_pull_len(struct logger_log *log, size_t from, size_t len)
+{
+ size_t skip_len;
+
+ if (from > log->w_off)
+ skip_len = from - log->w_off;
+ else
+ skip_len = log->size - (log->w_off - from);
+
+ /* +1 so that w_off and r_off don't collide */
+ return (len - skip_len) + 1;
+}
+
+/*
* fix_up_readers - walk the list of all readers and "fix up" any who were
* lapped by the writer; also do the same for the default "start head".
* We do this by "pulling forward" the readers and start head to the first
@@ -377,14 +395,25 @@ static void fix_up_readers(struct logger_log *log, size_t len)
{
size_t old = log->w_off;
size_t new = logger_offset(log, old + len);
+ size_t pull, fix = 0;
struct logger_reader *reader;
- if (is_between(old, new, log->head))
- log->head = get_next_entry(log, log->head, len);
+ if (is_between(old, new, log->head)) {
+ pull = find_pull_len(log, log->head, len);
+ fix = get_next_entry(log, log->head, pull);
+ log->head = fix;
+ }
list_for_each_entry(reader, &log->readers, list)
- if (is_between(old, new, reader->r_off))
- reader->r_off = get_next_entry(log, reader->r_off, len);
+ if (is_between(old, new, reader->r_off)) {
+ if (fix) {
+ reader->r_off = fix;
+ } else {
+ pull = find_pull_len(log, reader->r_off, len);
+ fix = get_next_entry(log, reader->r_off, pull);
+ reader->r_off = fix;
+ }
+ }
}
/*
--
1.7.9.5
