[PATCH v4 07/13] Add support for async close of client RPC socket

[Jiri Denemark <jdenemar@xxxxxxxxxx>]

---
Notes:
    ACKed

    Version 4:
    - no changes
    
    Version 3:
    - no changes
    
    Version 2:
    - no changes

 src/rpc/virnetclient.c |   76 ++++++++++++++++++++++++++++++++++++++++++------
 1 files changed, 67 insertions(+), 9 deletions(-)

diff --git a/src/rpc/virnetclient.c b/src/rpc/virnetclient.c
index 58ba66d..aaf072a 100644
--- a/src/rpc/virnetclient.c
+++ b/src/rpc/virnetclient.c
@@ -95,9 +95,13 @@ struct _virNetClient {
 
     size_t nstreams;
     virNetClientStreamPtr *streams;
+
+    bool wantClose;
 };
 
 
+void virNetClientRequestClose(virNetClientPtr client);
+
 static int virNetClientSendInternal(virNetClientPtr client,
                                     virNetMessagePtr msg,
                                     bool expectReply,
@@ -307,12 +311,14 @@ void virNetClientFree(virNetClientPtr client)
 }
 
 
-void virNetClientClose(virNetClientPtr client)
+static void
+virNetClientCloseLocked(virNetClientPtr client)
 {
-    if (!client)
+    VIR_DEBUG("client=%p, sock=%p", client, client->sock);
+
+    if (!client->sock)
         return;
 
-    virNetClientLock(client);
     virNetSocketRemoveIOCallback(client->sock);
     virNetSocketFree(client->sock);
     client->sock = NULL;
@@ -322,6 +328,41 @@ void virNetClientClose(virNetClientPtr client)
     virNetSASLSessionFree(client->sasl);
     client->sasl = NULL;
 #endif
+    client->wantClose = false;
+}
+
+void virNetClientClose(virNetClientPtr client)
+{
+    if (!client)
+        return;
+
+    virNetClientLock(client);
+    virNetClientCloseLocked(client);
+    virNetClientUnlock(client);
+}
+
+void
+virNetClientRequestClose(virNetClientPtr client)
+{
+    VIR_DEBUG("client=%p", client);
+
+    virNetClientLock(client);
+
+    /* If there is a thread polling for data on the socket, set wantClose flag
+     * and wake the thread up or just immediately close the socket when no-one
+     * is polling on it.
+     */
+    if (client->waitDispatch) {
+        char ignore = 1;
+        int len = sizeof(ignore);
+
+        client->wantClose = true;
+        if (safewrite(client->wakeupSendFD, &ignore, len) != len)
+            VIR_ERROR(_("failed to wake up polling thread"));
+    } else {
+        virNetClientCloseLocked(client);
+    }
+
     virNetClientUnlock(client);
 }
 
@@ -978,11 +1019,12 @@ static int virNetClientIOEventLoop(virNetClientPtr client,
         sigset_t oldmask, blockedsigs;
         int timeout = -1;
 
-        /* If we have existing SASL decoded data we
-         * don't want to sleep in the poll(), just
-         * check if any other FDs are also ready
+        /* If we have existing SASL decoded data we don't want to sleep in
+         * the poll(), just check if any other FDs are also ready.
+         * If the connection is going to be closed, we don't want to sleep in
+         * poll() either.
          */
-        if (virNetSocketHasCachedData(client->sock))
+        if (virNetSocketHasCachedData(client->sock) || client->wantClose)
             timeout = 0;
 
         fds[0].events = fds[0].revents = 0;
@@ -1047,6 +1089,11 @@ static int virNetClientIOEventLoop(virNetClientPtr client,
         if (virNetSocketHasCachedData(client->sock))
             fds[0].revents |= POLLIN;
 
+        /* If wantClose flag is set, pretend there was an error on the socket
+         */
+        if (client->wantClose)
+            fds[0].revents = POLLERR;
+
         if (fds[1].revents) {
             VIR_DEBUG("Woken up from poll by other thread");
             if (saferead(client->wakeupReadFD, &ignore, sizeof(ignore)) != sizeof(ignore)) {
@@ -1140,6 +1187,8 @@ pass:
     if (client->waitDispatch) {
         VIR_DEBUG("Passing the buck to %p", client->waitDispatch);
         virCondSignal(&client->waitDispatch->cond);
+    } else if (client->wantClose) {
+        virNetClientCloseLocked(client);
     }
     return ret;
 }
@@ -1281,7 +1330,8 @@ static int virNetClientIO(virNetClientPtr client,
     virResetLastError();
     rv = virNetClientIOEventLoop(client, thiscall);
 
-    virNetSocketUpdateIOCallback(client->sock, VIR_EVENT_HANDLE_READABLE);
+    if (client->sock)
+        virNetSocketUpdateIOCallback(client->sock, VIR_EVENT_HANDLE_READABLE);
 
     if (rv == 0 &&
         virGetLastError())
@@ -1305,7 +1355,7 @@ void virNetClientIncomingEvent(virNetSocketPtr sock,
         goto done;
 
     /* This should be impossible, but it doesn't hurt to check */
-    if (client->waitDispatch)
+    if (client->waitDispatch || client->wantClose)
         goto done;
 
     VIR_DEBUG("Event fired %p %d", sock, events);
@@ -1357,6 +1407,12 @@ virNetClientSendInternal(virNetClientPtr client,
 
     virNetClientLock(client);
 
+    if (!client->sock || client->wantClose) {
+        virNetError(VIR_ERR_INTERNAL_ERROR, "%s",
+                    _("Client socket is closed"));
+        goto unlock;
+    }
+
     /* We don't need call->cond for non-blocking calls since there's no
      * thread to be woken up anyway
      */
@@ -1396,6 +1452,8 @@ cleanup:
     } else {
         VIR_FREE(call);
     }
+
+unlock:
     virNetClientUnlock(client);
     return ret;
 }
-- 
1.7.7.1

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