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Code polishing.

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This commit is contained in:
vraatikka
2013-07-26 21:46:23 +03:00
parent ff8b432943
commit 3989615197
1 changed files with 25 additions and 21 deletions
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46
log_manager/log_manager.cc
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@ -1444,18 +1444,22 @@ static void filewriter_done(
* with spinlock. Another protected section is when block buffer's metadata is
* read, and optionally the write operation.
*
* When block buffer is marked full or flush flag is set, they don't try to
* access buffer. There may, however, be active writes, on the block in parallel
* with file writer operations. Each active write corresponds to bb_refcounter
* values. File writer doesn't write block buffer before its refcount is zero.
* When block buffer is marked full, logfile's flushflag is set, other
* log clients don't try to access buffer(s). There may, however, be
* active writes, on the block in parallel with file writer operations.
* Each active write corresponds to bb_refcounter values.
* On the other hand, file writer doesn't process the block buffer before
* its refcount is zero.
*
* Block buffers are located in a linked list. List is accessed by log clients,
* which add nodes if necessary, and by file writer which traverses the list
* and accesses block buffers included in list nodes. List modifications are
* protected with version numbers. Before modification, version is increased
* by one to be odd. After the completion, it is increased again to even. List
* can be read only when version is even and read is consistent only if version
* hasn't changed during the read.
* Every log file obj. has its own block buffer (linked) list.
* List is accessed by log clients, which add nodes if necessary, and
* by file writer which traverses the list and accesses block buffers
* included in list nodes.
* List modifications are protected with version numbers.
* Before modification, version is increased by one to be odd. After the
* completion, it is increased again to even. List can be read only when
* version is even and read is consistent only if version hasn't changed
* during the read.
*/
static void* thr_filewriter_fun(
void* data)
@ -1469,8 +1473,9 @@ static void* thr_filewriter_fun(
blockbuf_t* bb;
mlist_node_t* node;
int i;
bool flush; /**< flush logfile */
bool flushall;/**< flush all logfiles */
bool flush_blockbuf; /**< flush single block buffer. */
bool flush_logfile; /**< flush logfile */
bool flushall_logfiles;/**< flush all logfiles */
size_t vn1;
size_t vn2;
@ -1489,7 +1494,7 @@ static void* thr_filewriter_fun(
*/
skygw_message_wait(fwr->fwr_logmes);
flushall = skygw_thread_must_exit(thr);
flushall_logfiles = skygw_thread_must_exit(thr);
/** Process all logfiles which have buffered writes. */
for (i=LOGFILE_FIRST; i<=LOGFILE_LAST; i++) {
@ -1503,7 +1508,7 @@ static void* thr_filewriter_fun(
* read and reset logfile's flushflag
*/
acquire_lock(&lf->lf_spinlock);
flush = lf->lf_flushflag;
flush_logfile = lf->lf_flushflag;
lf->lf_flushflag = FALSE;
release_lock(&lf->lf_spinlock);
@ -1523,8 +1528,10 @@ static void* thr_filewriter_fun(
/** Lock block buffer */
simple_mutex_lock(&bb->bb_mutex, TRUE);
flush_blockbuf = bb->bb_isfull;
if (bb->bb_buf_used != 0 &&
(bb->bb_isfull || flush || flushall))
(flush_blockbuf || flush_logfile || flushall_logfiles))
{
/**
* buffer is at least half-full -> write to disk
@ -1537,12 +1544,9 @@ static void* thr_filewriter_fun(
skygw_file_write(file,
(void *)bb->bb_buf,
bb->bb_buf_used,
(flush || flushall)); /**< call fsync */
(flush_logfile || flushall_logfiles));
/**
* Reset buffer
* NOTE: it may be probably faster to free and calloc
* new buffer every time full one is locked for
* file write.
* Reset buffer's counters and mark not full.
*/
bb->bb_buf_left = bb->bb_buf_size;
bb->bb_buf_used = 0;