[libvirt] PATCH: Remove linked list of clients in favour of an array

["Daniel P. Berrange" <berrange@xxxxxxxxxx>]

More preparation for multi-thread support, this time in the libvirtd
daemon. This removes the embedded linked list of 'struct qemud_client'
and replaces it with an explicit array of pointers of client objects.
This makes per-client locking more practical in a patch to follow.
This touches suprisingly little code :-)

 qemud.c |   43 ++++++++++++++++++++++++-------------------
 qemud.h |    4 +---
 2 files changed, 25 insertions(+), 22 deletions(-)

Daniel


diff --git a/qemud/qemud.c b/qemud/qemud.c
--- a/qemud/qemud.c
+++ b/qemud/qemud.c
@@ -1086,6 +1086,12 @@ static int qemudDispatchServer(struct qe
         return -1;
     }
 
+    if (VIR_REALLOC_N(server->clients, server->nclients+1) < 0) {
+        qemudLog(QEMUD_ERR, "%s", _("Out of memory allocating clients"));
+        close(fd);
+        return -1;
+    }
+
     /* Disable Nagle.  Unix sockets will ignore this. */
     setsockopt (fd, IPPROTO_TCP, TCP_NODELAY, (void *)&no_slow_start,
                 sizeof no_slow_start);
@@ -1165,9 +1171,7 @@ static int qemudDispatchServer(struct qe
         }
     }
 
-    client->next = server->clients;
-    server->clients = client;
-    server->nclients++;
+    server->clients[server->nclients++] = client;
 
     return 0;
 
@@ -1182,19 +1186,19 @@ static int qemudDispatchServer(struct qe
 
 
 static void qemudDispatchClientFailure(struct qemud_server *server, struct qemud_client *client) {
-    struct qemud_client *tmp = server->clients;
-    struct qemud_client *prev = NULL;
-    while (tmp) {
-        if (tmp == client) {
-            if (prev == NULL)
-                server->clients = client->next;
-            else
-                prev->next = client->next;
-            server->nclients--;
+    int i, n = -1;
+    for (i = 0 ; i < server->nclients ; i++) {
+        if (server->clients[i] == client) {
+            n = i;
             break;
         }
-        prev = tmp;
-        tmp = tmp->next;
+    }
+    if (n != -1) {
+        if (n < (server->nclients-1))
+            memmove(server->clients + n,
+                    server->clients + n + 1,
+                    server->nclients - (n + 1));
+        server->nclients--;
     }
 
     virEventRemoveHandleImpl(client->fd);
@@ -1554,13 +1558,14 @@ static void qemudDispatchClientWrite(str
 
 static void qemudDispatchClientEvent(int fd, int events, void *opaque) {
     struct qemud_server *server = (struct qemud_server *)opaque;
-    struct qemud_client *client = server->clients;
+    struct qemud_client *client = NULL;
+    int i;
 
-    while (client) {
-        if (client->fd == fd)
+    for (i = 0 ; i < server->nclients ; i++) {
+        if (server->clients[i]->fd == fd) {
+            client = server->clients[i];
             break;
-
-        client = client->next;
+        }
     }
 
     if (!client)
diff --git a/qemud/qemud.h b/qemud/qemud.h
--- a/qemud/qemud.h
+++ b/qemud/qemud.h
@@ -131,8 +131,6 @@ struct qemud_client {
      * called, it will be set back to NULL if that succeeds.
      */
     virConnectPtr conn;
-
-    struct qemud_client *next;
 };
 
 #define QEMUD_CLIENT_MAGIC 0x7788aaee
@@ -152,7 +150,7 @@ struct qemud_server {
     int nsockets;
     struct qemud_socket *sockets;
     int nclients;
-    struct qemud_client *clients;
+    struct qemud_client **clients;
     int sigread;
     char logDir[PATH_MAX];
     unsigned int shutdown : 1;

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