Introduce virConnectSetKeepAlive

virConnectSetKeepAlive public API can be used by a client connecting to
remote server to start using keepalive protocol. The API is handled
directly by remote driver and not transmitted over the wire to the
server.

include/libvirt/libvirt.h.in

@@ -3387,6 +3387,10 @@ typedef struct _virTypedParameter virMemoryParameter;
  */
 typedef virMemoryParameter *virMemoryParameterPtr;
 
+int virConnectSetKeepAlive(virConnectPtr conn,
+                           int interval,
+                           unsigned int count);
+
 #ifdef __cplusplus
 }
 #endif

src/driver.h

@@ -740,6 +740,10 @@ typedef int
     (*virDrvDomainBlockPull)(virDomainPtr dom, const char *path,
                              unsigned long bandwidth, unsigned int flags);
 
+typedef int
+    (*virDrvSetKeepAlive)(virConnectPtr conn,
+                          int interval,
+                          unsigned int count);
 
 /**
  * _virDriver:
@@ -899,6 +903,7 @@ struct _virDriver {
     virDrvDomainGetBlockJobInfo domainGetBlockJobInfo;
     virDrvDomainBlockJobSetSpeed domainBlockJobSetSpeed;
     virDrvDomainBlockPull domainBlockPull;
+    virDrvSetKeepAlive setKeepAlive;
 };
 
 typedef int

src/libvirt.c

@@ -17188,3 +17188,61 @@ error:
     virDispatchError(dom->conn);
     return -1;
 }
+
+
+/**
+ * virConnectSetKeepAlive:
+ * @conn: pointer to a hypervisor connection
+ * @interval: number of seconds of inactivity before a keepalive message is sent
+ * @count: number of messages that can be sent in a row
+ *
+ * Start sending keepalive messages after interval second of inactivity and
+ * consider the connection to be broken when no response is received after
+ * count keepalive messages sent in a row.  In other words, sending count + 1
+ * keepalive message results in closing the connection.  When interval is <= 0,
+ * no keepalive messages will be sent.  When count is 0, the connection will be
+ * automatically closed after interval seconds of inactivity without sending
+ * any keepalive messages.
+ *
+ * Note: client has to implement and run event loop to be able to use keepalive
+ * messages.  Failure to do so may result in connections being closed
+ * unexpectedly.
+ *
+ * Returns -1 on error, 0 on success, 1 when remote party doesn't support
+ * keepalive messages.
+ */
+int virConnectSetKeepAlive(virConnectPtr conn,
+                           int interval,
+                           unsigned int count)
+{
+    int ret = -1;
+
+    VIR_DEBUG("conn=%p, interval=%d, count=%u", conn, interval, count);
+
+    virResetLastError();
+
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(VIR_ERR_INVALID_CONN, __FUNCTION__);
+        virDispatchError(NULL);
+        return -1;
+    }
+
+    if (interval <= 0) {
+        virLibConnError(VIR_ERR_INVALID_ARG,
+                        _("negative or zero interval make no sense"));
+        goto error;
+    }
+
+    if (conn->driver->setKeepAlive) {
+        ret = conn->driver->setKeepAlive(conn, interval, count);
+        if (ret < 0)
+            goto error;
+        return ret;
+    }
+
+    virLibConnError(VIR_ERR_NO_SUPPORT, __FUNCTION__);
+
+error:
+    virDispatchError(conn);
+    return -1;
+}

src/libvirt_internal.h

@@ -39,8 +39,8 @@ int virStateActive(void);
  *
  * The remote driver passes features through to the real driver at the
  * remote end unmodified, except if you query a VIR_DRV_FEATURE_REMOTE*
- * feature.
- *
+ * feature.  Queries for VIR_DRV_FEATURE_PROGRAM* features are answered
+ * directly by the RPC layer and not by the real driver.
  */
 enum {
     /* Driver supports V1-style virDomainMigrate, ie. domainMigratePrepare/
@@ -89,6 +89,12 @@ enum {
      * Support for VIR_TYPED_PARAM_STRING
      */
     VIR_DRV_FEATURE_TYPED_PARAM_STRING = 9,
+
+    /*
+     * Remote party supports keepalive program (i.e., sending keepalive
+     * messages).
+     */
+    VIR_DRV_FEATURE_PROGRAM_KEEPALIVE = 10,
 };
 
 

src/libvirt_public.syms

@@ -498,4 +498,9 @@ LIBVIRT_0.9.7 {
         virDomainSnapshotNumChildren;
 } LIBVIRT_0.9.5;
 
+LIBVIRT_0.9.8 {
+    global:
+        virConnectSetKeepAlive;
+} LIBVIRT_0.9.7;
+
 # .... define new API here using predicted next version number ....

src/util/event.c

@@ -193,9 +193,9 @@ void virEventRegisterImpl(virEventAddHandleFunc addHandle,
  * not have a need to integrate with an external event
  * loop impl.
  *
- * Once registered, the application can invoke
- * virEventRunDefaultImpl in a loop to process
- * events
+ * Once registered, the application has to invoke virEventRunDefaultImpl in
+ * a loop to process events.  Failure to do so may result in connections being
+ * closed unexpectedly as a result of keepalive timeout.
  *
  * Returns 0 on success, -1 on failure.
  */