[PATCH v3 3/3] gluster: cache glfs connection object per volume

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Currently, in case if we have 4 extra attached disks, then for each disk
we need to call 'glfs_init' (over network) and friends which could be costly.

Additionally snapshot(external) scenario will further complex the situation.

This patch maintain a cache of glfs objects per volume, hence the
all disks/snapshots belonging to the volume whose glfs object is cached
can avoid calls to 'glfs_init' and friends by simply taking a ref on
existing object.

The glfs object is shared only if volume name and all the volfile servers match
(includes hostname, transport and port number).

Thanks to 'Peter Krempa' for all the inputs.

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@xxxxxxxxxx>
---
 src/storage/storage_backend_fs.c      |   2 +
 src/storage/storage_backend_gluster.c | 249 +++++++++++++++++++++++++++++++---
 src/storage/storage_driver.c          |   5 +-
 3 files changed, 230 insertions(+), 26 deletions(-)

diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
index de0e8d5..0e03e06 100644
--- a/src/storage/storage_backend_fs.c
+++ b/src/storage/storage_backend_fs.c
@@ -1488,6 +1488,8 @@ virStorageFileBackendFileDeinit(virStorageSourcePtr src)
 
     VIR_FREE(priv->canonpath);
     VIR_FREE(priv);
+
+    VIR_FREE(src->drv);
 }
 
 
diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c
index 0d5b7f6..1f85dfa 100644
--- a/src/storage/storage_backend_gluster.c
+++ b/src/storage/storage_backend_gluster.c
@@ -31,11 +31,26 @@
 #include "virstoragefile.h"
 #include "virstring.h"
 #include "viruri.h"
+#include "viratomic.h"
 
 #define VIR_FROM_THIS VIR_FROM_STORAGE
 
 VIR_LOG_INIT("storage.storage_backend_gluster");
 
+
+typedef struct _virStorageBackendGlusterState virStorageBackendGlusterState;
+typedef virStorageBackendGlusterState *virStorageBackendGlusterStatePtr;
+
+typedef struct _virStorageFileBackendGlusterPriv virStorageFileBackendGlusterPriv;
+typedef virStorageFileBackendGlusterPriv *virStorageFileBackendGlusterPrivPtr;
+
+typedef struct _virStorageBackendGlusterStatePreopened virStorageBackendGlusterStatePreopened;
+typedef virStorageBackendGlusterStatePreopened *virStorageBackendGlusterStatePtrPreopened;
+
+typedef struct _virStorageBackendGlusterconnCache virStorageBackendGlusterconnCache;
+typedef virStorageBackendGlusterconnCache *virStorageBackendGlusterconnCachePtr;
+
+
 struct _virStorageBackendGlusterState {
     glfs_t *vol;
 
@@ -47,8 +62,207 @@ struct _virStorageBackendGlusterState {
     char *dir; /* dir from URI, or "/"; always starts and ends in '/' */
 };
 
-typedef struct _virStorageBackendGlusterState virStorageBackendGlusterState;
-typedef virStorageBackendGlusterState *virStorageBackendGlusterStatePtr;
+struct _virStorageFileBackendGlusterPriv {
+    glfs_t *vol;
+    char *canonpath;
+};
+
+struct _virStorageBackendGlusterStatePreopened {
+    virObjectLockable parent;
+    virStorageFileBackendGlusterPrivPtr priv;
+    size_t nservers;
+    virStorageNetHostDefPtr hosts;
+    char *volname;
+};
+
+struct _virStorageBackendGlusterconnCache {
+    virMutex lock;
+    size_t nConn;
+    virStorageBackendGlusterStatePtrPreopened *conn;
+};
+
+
+static virStorageBackendGlusterconnCachePtr connCache;
+static virClassPtr virStorageBackendGlusterStatePreopenedClass;
+static virOnceControl glusterConnOnce = VIR_ONCE_CONTROL_INITIALIZER;
+static bool virStorageBackendGlusterPreopenedGlobalError;
+
+
+static void virStorageBackendGlusterStatePreopenedDispose(void *obj);
+
+
+static int virStorageBackendGlusterStatePreopenedOnceInit(void)
+{
+    if (!(virStorageBackendGlusterStatePreopenedClass =
+                                virClassNew(virClassForObjectLockable(),
+                                "virStorageBackendGlusterStatePreopenedClass",
+                                sizeof(virStorageBackendGlusterStatePreopened),
+                                virStorageBackendGlusterStatePreopenedDispose)))
+        return -1;
+
+    return 0;
+}
+
+static void virStorageBackendGlusterStatePreopenedDispose(void *object)
+{
+    virStorageBackendGlusterStatePtrPreopened entry = object;
+
+    glfs_fini(entry->priv->vol);
+
+    VIR_FREE(entry->priv->canonpath);
+    VIR_FREE(entry->priv);
+    VIR_FREE(entry->volname);
+
+    virStorageNetHostDefFree(entry->nservers, entry->hosts);
+}
+
+static void
+virStorageBackendGlusterConnInit(void)
+{
+    if (VIR_ALLOC(connCache) < 0) {
+        virStorageBackendGlusterPreopenedGlobalError = false;
+        return;
+    }
+
+    if (virMutexInit(&connCache->lock) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("Unable to initialize mutex"));
+        virStorageBackendGlusterPreopenedGlobalError = false;
+    }
+}
+
+VIR_ONCE_GLOBAL_INIT(virStorageBackendGlusterStatePreopened);
+
+static int
+virStorageBackendGlusterPreopenedSet(virStorageSourcePtr src,
+                                     virStorageFileBackendGlusterPrivPtr priv)
+{
+    size_t i;
+    virStorageBackendGlusterStatePtrPreopened entry = NULL;
+
+    if (virOnce(&glusterConnOnce, virStorageBackendGlusterConnInit) < 0)
+        return -1;
+
+    if (virStorageBackendGlusterPreopenedGlobalError)
+        return -1;
+
+    virMutexLock(&connCache->lock);
+    for (i = 0; i < connCache->nConn; i++) {
+        if (STREQ(connCache->conn[i]->volname, src->volume)) {
+            virMutexUnlock(&connCache->lock);
+            return 0;
+        }
+    }
+    virMutexUnlock(&connCache->lock);
+
+    if (virStorageBackendGlusterStatePreopenedInitialize() < 0)
+        return -1;
+
+    if (!(entry = virObjectLockableNew(virStorageBackendGlusterStatePreopenedClass)))
+        return -1;
+
+    if (VIR_STRDUP(entry->volname, src->volume) < 0)
+        goto error;
+
+    if (VIR_ALLOC_N(entry->hosts, entry->nservers) < 0)
+        goto error;
+
+    entry->nservers = src->nhosts;
+    if (!(entry->hosts = virStorageNetHostDefCopy(src->nhosts, src->hosts)))
+        goto error;
+    entry->priv = priv;
+
+    virMutexLock(&connCache->lock);
+    if (VIR_APPEND_ELEMENT(connCache->conn, connCache->nConn, entry) < 0) {
+        virMutexUnlock(&connCache->lock);
+        goto error;
+    }
+    virMutexUnlock(&connCache->lock);
+
+    return 0;
+
+ error:
+    virStorageNetHostDefFree(entry->nservers, entry->hosts);
+    VIR_FREE(entry->volname);
+    return -1;
+}
+
+static glfs_t *
+virStorageBackendGlusterPreopenedFind(virStorageSourcePtr src)
+{
+    glfs_t *ret = NULL;
+    bool match = false;
+    size_t i;
+    size_t j;
+    size_t k;
+
+    if (connCache == NULL)
+        return NULL;
+
+    virStorageBackendGlusterStatePtrPreopened entry;
+
+    virMutexLock(&connCache->lock);
+    for (i = 0; i < connCache->nConn; i++) {
+        entry = connCache->conn[i];
+        if (!(STREQ(entry->volname, src->volume) &&
+            (entry->nservers == src->nhosts)))
+            continue;
+        for (j = 0; j < entry->nservers; j++) {
+            for (k = 0; k < src->nhosts; k++) {
+                if (entry->hosts[j].type != src->hosts[k].type)
+                    continue;
+                if (entry->hosts[j].type == VIR_STORAGE_NET_HOST_TRANS_UNIX) {
+                    if (STREQ(entry->hosts[j].u.uds.path,
+                              src->hosts[k].u.uds.path)) {
+                        match = true;
+                        break;
+                    }
+                } else {
+                    if (STREQ(entry->hosts[j].u.inet.addr,
+                              src->hosts[k].u.inet.addr) &&
+                        STREQ(entry->hosts[j].u.inet.port,
+                              src->hosts[k].u.inet.port)) {
+                        match = true;
+                        break;
+                    }
+                }
+            }
+            if (!match)
+                goto unlock;
+            match = false; /* reset */
+        }
+        virObjectRef(entry);
+        ret = entry->priv->vol;
+    }
+
+ unlock:
+    virMutexUnlock(&connCache->lock);
+    return ret;
+}
+
+static void
+virStorageBackendGlusterPreopenedClose(virStorageSourcePtr src)
+{
+    virStorageFileBackendGlusterPrivPtr priv = src->drv->priv;
+    size_t i;
+
+    virMutexLock(&connCache->lock);
+    for (i = 0; i < connCache->nConn; i++) {
+        if (STREQ(connCache->conn[i]->volname, src->volume)) {
+            virObjectUnref(connCache->conn[i]);
+            if (connCache->conn[i]->volname) {
+                if (priv && priv->canonpath)
+                    VIR_FREE(priv->canonpath);
+                goto unlock;
+            }
+            VIR_DELETE_ELEMENT(connCache->conn, i, connCache->nConn);
+            VIR_FREE(src->drv);
+        }
+    }
+
+ unlock:
+    virMutexUnlock(&connCache->lock);
+}
 
 static void
 virStorageBackendGlusterClose(virStorageBackendGlusterStatePtr state)
@@ -538,31 +752,15 @@ virStorageBackend virStorageBackendGluster = {
 };
 
 
-typedef struct _virStorageFileBackendGlusterPriv virStorageFileBackendGlusterPriv;
-typedef virStorageFileBackendGlusterPriv *virStorageFileBackendGlusterPrivPtr;
-
-struct _virStorageFileBackendGlusterPriv {
-    glfs_t *vol;
-    char *canonpath;
-};
-
-
 static void
 virStorageFileBackendGlusterDeinit(virStorageSourcePtr src)
 {
-    virStorageFileBackendGlusterPrivPtr priv = src->drv->priv;
-
     VIR_DEBUG("deinitializing gluster storage file %p (gluster://%s:%s/%s%s)",
               src, src->hosts->u.inet.addr,
               src->hosts->u.inet.port ? src->hosts->u.inet.port : "0",
               src->volume, src->path);
 
-    if (priv->vol)
-        glfs_fini(priv->vol);
-    VIR_FREE(priv->canonpath);
-
-    VIR_FREE(priv);
-    src->drv->priv = NULL;
+    virStorageBackendGlusterPreopenedClose(src);
 }
 
 static int
@@ -626,6 +824,12 @@ virStorageFileBackendGlusterInit(virStorageSourcePtr src)
     if (VIR_ALLOC(priv) < 0)
         return -1;
 
+    priv->vol = virStorageBackendGlusterPreopenedFind(src);
+    if (priv->vol) {
+        src->drv->priv = priv;
+        return 0;
+    }
+
     VIR_DEBUG("initializing gluster storage file %p "
               "(priv='%p' volume='%s' path='%s') as [%u:%u]",
               src, priv, src->volume, src->path,
@@ -636,6 +840,9 @@ virStorageFileBackendGlusterInit(virStorageSourcePtr src)
         goto error;
     }
 
+    if (virStorageBackendGlusterPreopenedSet(src, priv) < 0)
+        goto error;
+
     for (i = 0; i < src->nhosts; i++) {
         if (virStorageFileBackendGlusterInitServer(priv, src->hosts + i) < 0)
             goto error;
@@ -653,9 +860,7 @@ virStorageFileBackendGlusterInit(virStorageSourcePtr src)
     return 0;
 
  error:
-    if (priv->vol)
-        glfs_fini(priv->vol);
-    VIR_FREE(priv);
+    virStorageBackendGlusterPreopenedClose(src);
 
     return -1;
 }
diff --git a/src/storage/storage_driver.c b/src/storage/storage_driver.c
index bf7c938..be69adf 100644
--- a/src/storage/storage_driver.c
+++ b/src/storage/storage_driver.c
@@ -2900,11 +2900,8 @@ virStorageFileDeinit(virStorageSourcePtr src)
     if (!virStorageFileIsInitialized(src))
         return;
 
-    if (src->drv->backend &&
-        src->drv->backend->backendDeinit)
+    if (src->drv->backend && src->drv->backend->backendDeinit)
         src->drv->backend->backendDeinit(src);
-
-    VIR_FREE(src->drv);
 }
 
 
-- 
2.7.4

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