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engine: better transport timeout handling 

Use the monotonic system time. Timespec has sub-second resolution and
by using the monotonic time, we are independent of time corrections.

If retryDuration is smaller than retryInterval, then time out after
retryDuration instead of waiting once for retryInterval and then
checking retryDuration.

When the request timed out *exactly* after retryDuration or the next
resend would happen after the retryDuration, then give up immediately.
This commit is contained in:
Patrick Ohly 2013-04-24 10:01:54 +02:00
parent e891851b0f
commit e154b747d2
1 changed files with 27 additions and 20 deletions
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47
src/syncevo/SyncContext.cpp
View File

@ -1599,7 +1599,7 @@ boost::shared_ptr<TransportAgent> SyncContext::createTransportAgent(void *gmainl
string url = getUsedSyncURL();
m_retryInterval = getRetryInterval();
m_retryDuration = getRetryDuration();
int timeout = m_serverMode ? m_retryDuration : m_retryInterval;
int timeout = m_serverMode ? m_retryDuration : min(m_retryInterval, m_retryDuration);
if (m_localSync) {
string peer = url.substr(strlen("local://"));
@ -3577,7 +3577,7 @@ SyncMLStatus SyncContext::doSync()
// parameter STEPCMD_ABORT -> abort session as soon as possible.
bool aborting = false;
int suspending = 0;
time_t sendStart = 0, resendStart = 0;
Timespec sendStart, resendStart;
int requestNum = 0;
sysync::uInt16 previousStepCmd = stepCmd;
do {
@ -3772,8 +3772,8 @@ SyncMLStatus SyncContext::doSync()
"contenttype");
m_agent->setContentType(s);
sessionKey.reset();
sendStart = resendStart = time (NULL);
sendStart = resendStart = Timespec::monotonic();
requestNum ++;
// use GetSyncMLBuffer()/RetSyncMLBuffer() to access the data to be
// sent or have it copied into caller's buffer using
@ -3785,7 +3785,7 @@ SyncMLStatus SyncContext::doSync()
}
case sysync::STEPCMD_RESENDDATA: {
SE_LOG_INFO(NULL, "resend previous message, retry #%d", m_retries);
resendStart = time(NULL);
resendStart = Timespec::monotonic();
/* We are resending previous message, just read from the
* previous buffer */
m_agent->send(sendBuffer.get(), sendBuffer.size());
@ -3795,7 +3795,7 @@ SyncMLStatus SyncContext::doSync()
case sysync::STEPCMD_NEEDDATA:
if (!sendStart) {
// no message sent yet, record start of wait for data
sendStart = time(NULL);
sendStart = Timespec::monotonic();
}
switch (m_agent->wait()) {
case TransportAgent::ACTIVE:
@ -3804,21 +3804,23 @@ SyncMLStatus SyncContext::doSync()
break;
case TransportAgent::TIME_OUT: {
time_t duration = time(NULL) - sendStart;
double duration = (Timespec::monotonic() - sendStart).duration();
// HTTP SyncML servers cannot resend a HTTP POST
// reply. Other server transports could in theory
// resend, but don't have the necessary D-Bus APIs
// (MB #6370).
// Same if() as below for FAILED.
if (m_serverMode ||
!m_retryInterval || duration > m_retryDuration || requestNum == 1) {
!m_retryInterval || duration >= m_retryDuration || requestNum == 1) {
SE_LOG_INFO(NULL,
"Transport giving up after %d retries and %ld:%02ldmin",
m_retries,
(long)(duration / 60),
(long)(duration % 60));
(long)duration / 60,
(long)duration % 60);
SE_THROW_EXCEPTION(TransportException, "timeout, retry period exceeded");
}else {
// Timeout must have been due to retryInterval having passed, resend
// immediately.
m_retries ++;
stepCmd = sysync::STEPCMD_RESENDDATA;
}
@ -3872,22 +3874,27 @@ SyncMLStatus SyncContext::doSync()
break;
}
time_t curTime = time(NULL);
time_t duration = curTime - sendStart;
// same if() as above for TIME_OUT
Timespec curTime = Timespec::monotonic();
double duration = (curTime - sendStart).duration();
double resendDelay = m_retryInterval - (curTime - resendStart).duration();
if (resendDelay < 0) {
resendDelay = 0;
}
// Similar if() as above for TIME_OUT. In addition, we must check that
// the next resend won't happen after the retryDuration, because then
// we might as well give up now immediately.
if (m_serverMode ||
!m_retryInterval || duration > m_retryDuration || requestNum == 1) {
!m_retryInterval || duration + resendDelay >= m_retryDuration || requestNum == 1) {
SE_LOG_INFO(NULL,
"Transport giving up after %d retries and %ld:%02ldmin",
m_retries,
(long)(duration / 60),
(long)(duration % 60));
(long)duration / 60,
(long)duration % 60);
SE_THROW_EXCEPTION(TransportException, "transport failed, retry period exceeded");
} else {
// retry send
int leftTime = m_retryInterval - (curTime - resendStart);
if (leftTime >0 ) {
if (Sleep(leftTime) > 0) {
// Resend after having ensured that the retryInterval is over.
if (resendDelay > 0) {
if (Sleep(resendDelay) > 0) {
if (checkForSuspend()) {
SE_LOG_DEBUG(NULL, "suspending after premature exit from sleep() caused by user suspend");
stepCmd = sysync::STEPCMD_SUSPEND;