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Fix more locking deadlocks

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Former-commit-id: 3081b6f98b5e7a9f3ef7cfe040236070398b081c
This commit is contained in:
John Sully 2019-07-12 23:51:45 -04:00
parent 8f1e7d9d5b
commit e78ed8cc64
3 changed files with 34 additions and 36 deletions
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2
src/debug.cpp
View File

@ -706,7 +706,7 @@ void _serverAssertPrintClientInfo(const client *c) {
bugReportStart();
serverLog(LL_WARNING,"=== ASSERTION FAILED CLIENT CONTEXT ===");
serverLog(LL_WARNING,"client->flags = %d", c->flags);
serverLog(LL_WARNING,"client->flags = %d", static_cast<int>(c->flags));
serverLog(LL_WARNING,"client->fd = %d", c->fd);
serverLog(LL_WARNING,"client->argc = %d", c->argc);
for (j=0; j < c->argc; j++) {

74
src/networking.cpp
View File

@ -1476,15 +1476,7 @@ int writeToClient(int fd, client *c, int handler_installed) {
serverLog(LL_VERBOSE,
"Error writing to client: %s", strerror(errno));
lock.unlock();
if (aeTryAcquireLock(true /*fWeak*/))
{
freeClient(c);
aeReleaseLock();
}
else
{
freeClientAsync(c);
}
return C_ERR;
}
@ -1503,15 +1495,7 @@ int writeToClient(int fd, client *c, int handler_installed) {
/* Close connection after entire reply has been sent. */
if (c->flags & CLIENT_CLOSE_AFTER_REPLY) {
lock.unlock();
if (aeTryAcquireLock(true /*fWeak*/))
{
freeClient(c);
aeReleaseLock();
}
else
{
freeClientAsync(c);
}
return C_ERR;
}
}
@ -1524,7 +1508,14 @@ void sendReplyToClient(aeEventLoop *el, int fd, void *privdata, int mask) {
client *c = (client*)privdata;
serverAssert(ielFromEventLoop(el) == c->iel);
writeToClient(fd,c,1);
if (writeToClient(fd,c,1) == C_ERR)
{
AeLocker ae;
c->lock.lock();
ae.arm(c);
if (c->flags & CLIENT_CLOSE_ASAP)
freeClient(c);
}
}
void ProcessPendingAsyncWrites()
@ -1591,27 +1582,6 @@ int handleClientsWithPendingWrites(int iel) {
int processed = (int)vec.size();
serverAssert(iel == (serverTL - g_pserver->rgthreadvar));
while(!vec.empty()) {
client *c = vec.back();
std::unique_lock<decltype(c->lock)> lock(c->lock);
c->flags &= ~CLIENT_PENDING_WRITE;
vec.pop_back();
AssertCorrectThread(c);
/* If a client is protected, don't do anything,
* that may trigger write error or recreate handler. */
if (c->flags & CLIENT_PROTECTED) continue;
/* Try to write buffers to the client socket. */
if (writeToClient(c->fd,c,0) == C_ERR) {
lock.release(); // client is free'd
continue;
}
/* If after the synchronous writes above we still have data to
* output to the client, we need to install the writable handler. */
if (clientHasPendingReplies(c)) {
int ae_flags = AE_WRITABLE|AE_WRITE_THREADSAFE;
/* For the fsync=always policy, we want that a given FD is never
* served for reading and writing in the same event loop iteration,
@ -1624,6 +1594,34 @@ int handleClientsWithPendingWrites(int iel) {
ae_flags |= AE_BARRIER;
}
while(!vec.empty()) {
client *c = vec.back();
AssertCorrectThread(c);
c->flags &= ~CLIENT_PENDING_WRITE;
vec.pop_back();
/* If a client is protected, don't do anything,
* that may trigger write error or recreate handler. */
if (c->flags & CLIENT_PROTECTED) continue;
std::unique_lock<decltype(c->lock)> lock(c->lock);
/* Try to write buffers to the client socket. */
if (writeToClient(c->fd,c,0) == C_ERR) {
if (c->flags & CLIENT_CLOSE_ASAP)
{
c->lock.lock();
AeLocker ae;
ae.arm(c);
freeClient(c); // writeToClient will only async close, but there's no need to wait
}
continue;
}
/* If after the synchronous writes above we still have data to
* output to the client, we need to install the writable handler. */
if (clientHasPendingReplies(c)) {
if (aeCreateFileEvent(g_pserver->rgthreadvar[c->iel].el, c->fd, ae_flags, sendReplyToClient, c) == AE_ERR)
freeClientAsync(c);
}

2
src/server.h
View File

@ -921,7 +921,7 @@ typedef struct client {
time_t ctime; /* Client creation time. */
time_t lastinteraction; /* Time of the last interaction, used for timeout */
time_t obuf_soft_limit_reached_time;
int flags; /* Client flags: CLIENT_* macros. */
std::atomic<int> flags; /* Client flags: CLIENT_* macros. */
int fPendingAsyncWrite; /* NOTE: Not a flag because it is written to outside of the client lock (locked by the global lock instead) */
int authenticated; /* Needed when the default user requires auth. */
int replstate; /* Replication state if this is a slave. */