Author: Tsantilas Christos <chtsanti@users.sourceforge.net>

Add support for write timeouts.

The development sponsored by the Measurement Factory

Description:
The write I/O timeout should trigger if Squid has data to write but
the connection is not ready to accept more data for the specified time.
If the write times out, the Comm caller's write handler is called with
an ETIMEDOUT COMM_ERROR error.

Comm may process a single write request in several chunks, without
caller's knowledge. The waiting time is reset internally by Comm after
each chunk is written.

Default timeout value is 15 minutes.

The implementation requires no changes in Comm callers but it adds write
timeouts to all connections, including the connections that have
context-specific write timeouts. I think that is fine.

diff --git a/src/cf.data.pre b/src/cf.data.pre
index 79f17ff084fdf1ecd8f0e65b3c9b44d57ab03c07..961d8689ec73fb39a7bfcbd2d6667a99f8d7ea84 100644 (file)
--- a/src/cf.data.pre
+++ b/src/cf.data.pre
@@ -3986,6 +3986,21 @@ DOC_START
        default is 15 minutes.
 DOC_END
 
+NAME: write_timeout
+COMMENT: time-units
+TYPE: time_t
+LOC: Config.Timeout.write
+DEFAULT: 15 minutes
+DOC_START
+       This timeout is tracked for all connections that have data
+       available for writing and are waiting for the socket to become
+       ready. After each successful write, the timeout is extended by
+       the configured amount. If Squid has data to write but the
+       connection is not ready for the configured duration, the
+       transaction associated with the connection is terminated. The
+       default is 15 minutes.
+DOC_END
+
 NAME: request_timeout
 TYPE: time_t
 LOC: Config.Timeout.request

diff --git a/src/comm.cc b/src/comm.cc
index 3917b9514cbabf4ba2e2f100650d6a9d702fe4f7..0bcf565cf214705cbceb947e686ed6bee6c8476b 100644 (file)
--- a/src/comm.cc
+++ b/src/comm.cc
@@ -1991,6 +1991,9 @@ commHandleWrite(int fd, void *data)
     debugs(5, 5, "commHandleWrite: write() returns " << len);
     fd_bytes(fd, len, FD_WRITE);
     statCounter.syscalls.sock.writes++;
+    // After each successful partial write, 
+    // reset fde::writeStart to the current time. 
+    fd_table[fd].writeStart = squid_curtime;
 
     if (len == 0) {
         /* Note we even call write if nleft == 0 */
@@ -2062,6 +2065,7 @@ comm_write(int fd, const char *buf, int size, AsyncCall::Pointer &callback, FREE
     comm_io_callback_t *ccb = COMMIO_FD_WRITECB(fd);
     assert(!ccb->active());
 
+    fd_table[fd].writeStart = squid_curtime;
     /* Queue the write */
     commio_set_callback(fd, IOCB_WRITE, ccb, callback,
                         (char *)buf, free_func, size);
@@ -2162,6 +2166,18 @@ AlreadyTimedOut(fde *F)
     return false;
 }
 
+static bool
+writeTimedOut(int fd)
+{
+    if (!commio_has_callback(fd, IOCB_WRITE, COMMIO_FD_WRITECB(fd)))
+        return false;
+
+    if ((squid_curtime - fd_table[fd].writeStart) < Config.Timeout.write)
+        return false;
+
+    return true;
+}
+
 void
 checkTimeouts(void)
 {
@@ -2172,7 +2188,11 @@ checkTimeouts(void)
     for (fd = 0; fd <= Biggest_FD; fd++) {
         F = &fd_table[fd];
 
-        if (AlreadyTimedOut(F))
+        if (writeTimedOut(fd)) {
+            // We have an active write callback and we are timed out
+            commio_finish_callback(fd, COMMIO_FD_WRITECB(fd), COMM_ERROR, ETIMEDOUT);
+        }
+        else if (AlreadyTimedOut(F))
             continue;
 
         debugs(5, 5, "checkTimeouts: FD " << fd << " Expired");

diff --git a/src/fde.h b/src/fde.h
index 3b503d2b51e0e903db4d9173b8c85ae3c590726f..fa6ceff4043217d231cc3c3335c19e02fb85ec6a 100644 (file)
--- a/src/fde.h
+++ b/src/fde.h
@@ -94,6 +94,7 @@ public:
     void *write_data;
     AsyncCall::Pointer timeoutHandler;
     time_t timeout;
+    time_t writeStart;
     void *lifetime_data;
     AsyncCall::Pointer closeHandler;
     AsyncCall::Pointer halfClosedReader; /// read handler for half-closed fds

diff --git a/src/structs.h b/src/structs.h
index d9dafb6903bb14105bd87a3c707a0e2b3750ae73..1168c464f63e1cfd5c877744a542fcdba58ecc69 100644 (file)
--- a/src/structs.h
+++ b/src/structs.h
@@ -165,6 +165,7 @@ struct SquidConfig {
 
     struct {
         time_t read;
+        time_t write;
         time_t lifetime;
         time_t connect;
         time_t forward;