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Fix misuses of timeouts throughout the code.

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Prior to this change, a common method for determining if a timeout
was reached was to call a function such as ast_waitfor_n() and inspect
the out parameter that told how many milliseconds were left, then use
that as the input to ast_waitfor_n() on the next go-around.

The problem with this is that in some cases, submillisecond timeouts
can occur, resulting in the out parameter not decreasing any. When this
happens thousands of times, the result is that the timeout takes much
longer than intended to be reached. As an example, I had a situation where
a 3 second timeout took multiple days to finally end since most wakeups
from ast_waitfor_n() were under a millisecond.

This patch seeks to fix this pattern throughout the code. Now we log the
time when an operation began and find the difference in wall clock time
between now and when the event started. This means that sub-millisecond timeouts
now cannot play havoc when trying to determine if something has timed out.

Part of this fix also includes changing the function ast_waitfor() so that it
is possible for it to return less than zero when a negative timeout is given
to it. This makes it actually possible to detect errors in ast_waitfor() when
there is no timeout.

(closes issue ASTERISK-20414)
reported by David M. Lee

Review: https://reviewboard.asterisk.org/r/2135/



git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@375993 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Mark Michelson
2012-11-07 17:01:13 +00:00
parent 2fcf4a32a0
commit e95efa6c50
19 changed files with 318 additions and 163 deletions
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16
main/rtp_engine.c
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@@ -810,6 +810,7 @@ static enum ast_bridge_result local_bridge_loop(struct ast_channel *c0, struct a
enum ast_bridge_result res = AST_BRIDGE_FAILED;
struct ast_channel *who = NULL, *other = NULL, *cs[3] = { NULL, };
struct ast_frame *fr = NULL;
struct timeval start;
/* Start locally bridging both instances */
if (instance0->engine->local_bridge && instance0->engine->local_bridge(instance0, instance1)) {
@@ -840,7 +841,9 @@ static enum ast_bridge_result local_bridge_loop(struct ast_channel *c0, struct a
cs[0] = c0;
cs[1] = c1;
cs[2] = NULL;
start = ast_tvnow();
for (;;) {
int ms;
/* If the underlying formats have changed force this bridge to break */
if ((c0->rawreadformat != c1->rawwriteformat) || (c1->rawreadformat != c0->rawwriteformat)) {
ast_debug(1, "rtp-engine-local-bridge: Oooh, formats changed, backing out\n");
@@ -865,8 +868,9 @@ static enum ast_bridge_result local_bridge_loop(struct ast_channel *c0, struct a
break;
}
/* Wait on a channel to feed us a frame */
if (!(who = ast_waitfor_n(cs, 2, &timeoutms))) {
if (!timeoutms) {
ms = ast_remaining_ms(start, timeoutms);
if (!(who = ast_waitfor_n(cs, 2, &ms))) {
if (!ms) {
res = AST_BRIDGE_RETRY;
break;
}
@@ -985,6 +989,7 @@ static enum ast_bridge_result remote_bridge_loop(struct ast_channel *c0, struct
struct ast_sockaddr ac1 = {{0,}}, vac1 = {{0,}}, tac1 = {{0,}}, ac0 = {{0,}}, vac0 = {{0,}}, tac0 = {{0,}};
struct ast_sockaddr t1 = {{0,}}, vt1 = {{0,}}, tt1 = {{0,}}, t0 = {{0,}}, vt0 = {{0,}}, tt0 = {{0,}};
struct ast_frame *fr = NULL;
struct timeval start;
/* Test the first channel */
if (!(glue0->update_peer(c0, instance1, vinstance1, tinstance1, codec1, 0))) {
@@ -1024,7 +1029,9 @@ static enum ast_bridge_result remote_bridge_loop(struct ast_channel *c0, struct
cs[0] = c0;
cs[1] = c1;
cs[2] = NULL;
start = ast_tvnow();
for (;;) {
int ms;
/* Check if anything changed */
if ((c0->tech_pvt != pvt0) ||
(c1->tech_pvt != pvt1) ||
@@ -1115,9 +1122,10 @@ static enum ast_bridge_result remote_bridge_loop(struct ast_channel *c0, struct
oldcodec0 = codec0;
}
ms = ast_remaining_ms(start, timeoutms);
/* Wait for frame to come in on the channels */
if (!(who = ast_waitfor_n(cs, 2, &timeoutms))) {
if (!timeoutms) {
if (!(who = ast_waitfor_n(cs, 2, &ms))) {
if (!ms) {
res = AST_BRIDGE_RETRY;
break;
}