[libvirt] [PATCH v2 1/5] Add public API to register a callback to be invoked on connection close
Daniel P. Berrange
berrange at redhat.com
Tue Jul 24 13:17:01 UTC 2012
From: "Daniel P. Berrange" <berrange at redhat.com>
Define new virConnect{Register,Unregister}CloseCallback() public APIs
which allows registering/unregistering a callback to be invoked when
the connection to a hypervisor is closed. The callback is provided
with the reason for the close, which may be 'error', 'eof' or
'keepalive'.
Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
---
include/libvirt/libvirt.h.in | 49 +++++++++++++++----
src/datatypes.c | 3 ++
src/datatypes.h | 5 ++
src/libvirt.c | 111 ++++++++++++++++++++++++++++++++++++++++++
src/libvirt_public.syms | 2 +
5 files changed, 160 insertions(+), 10 deletions(-)
diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
index fcef461..d9f0397 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -49,6 +49,24 @@ extern "C" {
* defines VIR_ENUM_SENTINELS. Enumerations for bit values do not
* have a *_LAST value, but additional bits may be defined. */
+/*
+ * virFreeCallback:
+ * @opaque: opaque user data provided at registration
+ *
+ * Type for a callback cleanup function to be paired with a callback. This
+ * function will be called as a final chance to clean up the @opaque
+ * registered with the primary callback, at the time when the primary
+ * callback is deregistered.
+ *
+ * It is forbidden to call any other libvirt APIs from an
+ * implementation of this callback, since it can be invoked
+ * from a context which is not re-entrant safe. Failure to
+ * abide by this requirement may lead to application deadlocks
+ * or crashes.
+ */
+typedef void (*virFreeCallback)(void *opaque);
+
+
/**
* virConnect:
*
@@ -1148,6 +1166,27 @@ int virConnectSetKeepAlive(virConnectPtr conn,
int interval,
unsigned int count);
+typedef enum {
+ VIR_CONNECT_CLOSE_REASON_ERROR = 0, /* Misc I/O error */
+ VIR_CONNECT_CLOSE_REASON_EOF = 1, /* End-of-file from server */
+ VIR_CONNECT_CLOSE_REASON_KEEPALIVE = 2, /* Keepalive timer triggered */
+ VIR_CONNECT_CLOSE_REASON_CLIENT = 3, /* Client requested it */
+
+# ifdef VIR_ENUM_SENTINELS
+ VIR_CONNECT_CLOSE_REASON_LAST
+# endif
+} virConnectCloseReason;
+
+typedef void (*virConnectCloseFunc)(virConnectPtr conn,
+ int reason,
+ void *opaque);
+
+int virConnectRegisterCloseCallback(virConnectPtr conn,
+ virConnectCloseFunc cb,
+ void *opaque,
+ virFreeCallback freecb);
+int virConnectUnregisterCloseCallback(virConnectPtr conn,
+ virConnectCloseFunc cb);
/*
* Capabilities of the connection / driver.
@@ -2863,16 +2902,6 @@ typedef int (*virConnectDomainEventCallback)(virConnectPtr conn,
int detail,
void *opaque);
-/*
- * virFreeCallback:
- * @opaque: opaque user data provided at registration
- *
- * Type for a domain event callback when the event is deregistered and
- * need to be freed, @opaque is provided along with the callback at
- * registration time
- */
-typedef void (*virFreeCallback)(void *opaque);
-
int virConnectDomainEventRegister(virConnectPtr conn,
virConnectDomainEventCallback cb,
void *opaque,
diff --git a/src/datatypes.c b/src/datatypes.c
index 699c4a8..37a31d0 100644
--- a/src/datatypes.c
+++ b/src/datatypes.c
@@ -115,6 +115,9 @@ virReleaseConnect(virConnectPtr conn) {
virMutexLock(&conn->lock);
+ if (conn->closeFreeCallback)
+ conn->closeFreeCallback(conn->closeOpaque);
+
virResetError(&conn->err);
virURIFree(conn->uri);
diff --git a/src/datatypes.h b/src/datatypes.h
index 9ad2d01..8ac9171 100644
--- a/src/datatypes.h
+++ b/src/datatypes.h
@@ -187,6 +187,11 @@ struct _virConnect {
virErrorFunc handler; /* associated handlet */
void *userData; /* the user data */
+ /* Per-connection close callback */
+ virConnectCloseFunc closeCallback;
+ void *closeOpaque;
+ virFreeCallback closeFreeCallback;
+
int refs; /* reference count */
};
diff --git a/src/libvirt.c b/src/libvirt.c
index 8315b4f..9cfabc5 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -18613,6 +18613,117 @@ error:
/**
+ * virConnectRegisterCloseCallback:
+ * @conn: pointer to connection object
+ * @cb: callback to invoke upon close
+ * @opaque: user data to pass to @cb
+ * @freecb: callback to free @opaque
+ *
+ * Registers a callback to be invoked when the connection
+ * is closed. This callback is invoked when there is any
+ * condition that causes the socket connection to the
+ * hypervisor to be closed.
+ *
+ * This function is only applicable to hypervisor drivers
+ * which maintain a persistent open connection. Drivers
+ * which open a new connection for every operation will
+ * not invoke this.
+ *
+ * The @freecb must not invoke any other libvirt public
+ * APIs, since it is not called from a re-entrant safe
+ * context.
+ *
+ * Returns 0 on success, -1 on error
+ */
+int virConnectRegisterCloseCallback(virConnectPtr conn,
+ virConnectCloseFunc cb,
+ void *opaque,
+ virFreeCallback freecb)
+{
+ VIR_DEBUG("conn=%p", conn);
+
+ virResetLastError();
+
+ if (!VIR_IS_CONNECT(conn)) {
+ virLibConnError(VIR_ERR_INVALID_CONN, __FUNCTION__);
+ virDispatchError(NULL);
+ return -1;
+ }
+
+ virMutexLock(&conn->lock);
+
+ virCheckNonNullArgGoto(cb, error);
+
+ if (conn->closeCallback) {
+ virLibConnError(VIR_ERR_OPERATION_INVALID, "%s",
+ _("A close callback is already registered"));
+ goto error;
+ }
+
+ conn->closeCallback = cb;
+ conn->closeOpaque = opaque;
+ conn->closeFreeCallback = freecb;
+
+ virMutexUnlock(&conn->lock);
+
+ return 0;
+
+error:
+ virMutexUnlock(&conn->lock);
+ virDispatchError(NULL);
+ return -1;
+}
+
+/**
+ * virConnectUnregisterCloseCallback:
+ * @conn: pointer to connection object
+ * @cb: pointer to the current registered callback
+ *
+ * Unregisters the callback previously set with the
+ * virConnectRegisterCloseCallback method. The callback
+ * will no longer received notifications when the connection
+ * closes.
+ *
+ * Returns 0 on success, -1 on error
+ */
+int virConnectUnregisterCloseCallback(virConnectPtr conn,
+ virConnectCloseFunc cb)
+{
+ VIR_DEBUG("conn=%p", conn);
+
+ virResetLastError();
+
+ if (!VIR_IS_CONNECT(conn)) {
+ virLibConnError(VIR_ERR_INVALID_CONN, __FUNCTION__);
+ virDispatchError(NULL);
+ return -1;
+ }
+
+ virMutexLock(&conn->lock);
+
+ virCheckNonNullArgGoto(cb, error);
+
+ if (conn->closeCallback != cb) {
+ virLibConnError(VIR_ERR_OPERATION_INVALID, "%s",
+ _("A different callback was requested"));
+ goto error;
+ }
+
+ conn->closeCallback = NULL;
+ if (conn->closeFreeCallback)
+ conn->closeFreeCallback(conn->closeOpaque);
+
+ virMutexUnlock(&conn->lock);
+
+ return 0;
+
+error:
+ virMutexUnlock(&conn->lock);
+ virDispatchError(NULL);
+ return -1;
+}
+
+/**
* virDomainSetBlockIoTune:
* @dom: pointer to domain object
* @disk: path to the block device, or device shorthand
diff --git a/src/libvirt_public.syms b/src/libvirt_public.syms
index 1a8e58a..5004182 100644
--- a/src/libvirt_public.syms
+++ b/src/libvirt_public.syms
@@ -547,6 +547,8 @@ LIBVIRT_0.9.13 {
LIBVIRT_0.9.14 {
global:
virDomainGetHostname;
+ virConnectRegisterCloseCallback;
+ virConnectUnregisterCloseCallback;
} LIBVIRT_0.9.13;
# .... define new API here using predicted next version number ....
--
1.7.10.4
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