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libCom: Fix msgbufGetNode() in errlog.c

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Systems that generate large numbers of errlog messages or have a slow
message listener could overwrite older messages in the message buffer
after the buffer wraps.  This also corrects and annotates the test
code to describe what's being checked.
This commit is contained in:
Andrew Johnson
2011-03-01 15:03:33 -06:00
parent d73f466dbc
commit f4528ff5e1
2 changed files with 15 additions and 11 deletions
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6
src/libCom/error/errlog.c
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@@ -534,8 +534,10 @@ static msgNode *msgbufGetNode(void)
char *plimit = pbuffer + pvtData.buffersize;
pnextFree = plast->message + adjustToWorstCaseAlignment(plast->length);
if (pfirst <= plast &&
pnextFree + pvtData.msgNeeded > plimit) {
if (pfirst > plast) {
plimit = (char *)pfirst;
}
else if (pnextFree + pvtData.msgNeeded > plimit) {
pnextFree = pbuffer; /* Hit end, wrap to start */
plimit = (char *)pfirst;
}

20
src/libCom/test/epicsErrlogTest.c
View File

@@ -260,29 +260,31 @@ MAIN(epicsErrlogTest)
for (i = 0; i < N; i++) {
errlogPrintfNoConsole(msg);
}
epicsThreadSleep(0.1); /* should really be a second Event */
testOk1(pvt.count == 0);
epicsThreadSleep(0.1); /* should really be a second Event */
pvt.jam = -2; /* Block before #th message */
/* Extract the first 2 messages, 2*(sizeof(msgNode) + 128) bytes */
pvt.jam = -2;
epicsEventSignal(pvt.jammer);
epicsThreadSleep(0.1);
testDiag("Drain %u messages", pvt.count);
testDiag("Drained %u messages", pvt.count);
testOk1(pvt.count == 2);
testDiag("Add two more (%d total)", (int) N+2);
errlogPrintfNoConsole(msg);
/* The buffer has space for 1 more message: sizeof(msgNode) + 256 bytes */
errlogPrintfNoConsole(msg); /* Use up that space */
testDiag("Overflow the buffer");
errlogPrintfNoConsole(msg);
testOk1(pvt.count == 2);
epicsEventSignal(pvt.jammer);
epicsEventSignal(pvt.jammer); /* Empty */
errlogFlush();
testDiag("Logged %u messages", pvt.count);
testOk1(pvt.count == N+2);
testDiag("Logged %u messages", pvt.count);
testOk1(pvt.count == N+1);
/* Clean up */
errlogRemoveListener(&logClient);