Proper accounting of active TCP connections

diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index e233208d6f4e4f70f04ffcc261c1cdca25172785..481818857001f8b1a2284257f475eed65128b768 100644 (file)
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -369,7 +369,16 @@ struct isc_nmsocket {
         */
        isc_quota_t *quota;
        isc_quota_t *pquota;
-       bool overquota;
+
+       /*%
+        * How many connections we have not accepted due to quota?
+        * When we close a connection we need to accept a new one.
+        */
+       int overquota;
+       /*%
+        * How many active connections we have?
+        */
+       int conns;
 
        /*%
         * Socket statistics

diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index 81726b82a8c252aea43cfa5be38ab1b09fd87521..0e04dcb8af318ac7aa6426f8580448b67685c661 100644 (file)
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -718,6 +718,9 @@ nmsocket_cleanup(isc_nmsocket_t *sock, bool dofree) {
                for (int i = 0; i < sock->nchildren; i++) {
                        if (!atomic_load(&sock->children[i].destroying)) {
                                nmsocket_cleanup(&sock->children[i], false);
+                               if (sock->statsindex != NULL) {
+                                       isc__nm_decstats(sock->mgr, sock->statsindex[STATID_ACTIVE]);
+                               }
                        }
                }
 
@@ -729,6 +732,9 @@ nmsocket_cleanup(isc_nmsocket_t *sock, bool dofree) {
                sock->children = NULL;
                sock->nchildren = 0;
        }
+       if (sock->statsindex != NULL) {
+                       isc__nm_decstats(sock->mgr, sock->statsindex[STATID_ACTIVE]);
+       }
 
        if (sock->tcphandle != NULL) {
                isc_nmhandle_unref(sock->tcphandle);
@@ -843,8 +849,6 @@ isc__nmsocket_prep_destroy(isc_nmsocket_t *sock) {
        if (sock->children != NULL) {
                for (int i = 0; i < sock->nchildren; i++) {
                        atomic_store(&sock->children[i].active, false);
-                       isc__nm_decstats(sock->mgr,
-                                        sock->statsindex[STATID_ACTIVE]);
                }
        }
 

diff --git a/lib/isc/netmgr/tcp.c b/lib/isc/netmgr/tcp.c
index 6e6cee5a409a67a3595ed2a912e3891e13db888e..60ca097de0f81a9782593e3bbe4cdc22d16cd887 100644 (file)
--- a/lib/isc/netmgr/tcp.c
+++ b/lib/isc/netmgr/tcp.c
@@ -650,9 +650,6 @@ read_cb(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf) {
        }
 
        isc__nm_free_uvbuf(sock, buf);
-       if (sock->quota) {
-               isc_quota_detach(&sock->quota);
-       }
 
        /*
         * This might happen if the inner socket is closing.  It means that
@@ -680,6 +677,7 @@ accept_connection(isc_nmsocket_t *ssock) {
        struct sockaddr_storage ss;
        isc_sockaddr_t local;
        int r;
+       bool overquota = false;
 
        REQUIRE(VALID_NMSOCK(ssock));
        REQUIRE(ssock->tid == isc_nm_tid());
@@ -693,10 +691,26 @@ accept_connection(isc_nmsocket_t *ssock) {
 
        if (ssock->pquota != NULL) {
                result = isc_quota_attach(ssock->pquota, &quota);
+               /*
+                * We share the quota between sockets - we need to  have at
+                * least one active connection here to restart listening
+                * when the quota is available again (in tcp_close_direct).
+                */
                if (result != ISC_R_SUCCESS) {
-                       isc__nm_incstats(ssock->mgr,
-                                        ssock->statsindex[STATID_ACCEPTFAIL]);
-                       return (result);
+                       ssock->overquota++;
+                       overquota = true;
+                       if (ssock->conns > 0) {
+                               isc__nm_incstats(
+                                       ssock->mgr,
+                                       ssock->statsindex[STATID_ACCEPTFAIL]);
+                               return (result);
+                       }
+                       /*
+                        * We share the quota between sockets - we need to  have
+                        * at least one active connection here to restart
+                        * listening when the quota is available again (in
+                        * tcp_close_direct).
+                        */
                }
        }
 
@@ -743,6 +757,7 @@ accept_connection(isc_nmsocket_t *ssock) {
        }
 
        isc_nmsocket_attach(ssock, &csock->server);
+       ssock->conns++;
 
        handle = isc__nmhandle_get(csock, NULL, &local);
 
@@ -761,6 +776,9 @@ error:
        if (csock->quota != NULL) {
                isc_quota_detach(&csock->quota);
        }
+       if (overquota) {
+               ssock->overquota--;
+       }
        /* We need to detach it properly to make sure uv_close is called. */
        isc_nmsocket_detach(&csock);
        return (result);
@@ -775,9 +793,6 @@ tcp_connection_cb(uv_stream_t *server, int status) {
 
        result = accept_connection(ssock);
        if (result != ISC_R_SUCCESS) {
-               if (result == ISC_R_QUOTA || result == ISC_R_SOFTQUOTA) {
-                       ssock->overquota = true;
-               }
                isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
                              ISC_LOGMODULE_NETMGR, ISC_LOG_ERROR,
                              "TCP connection failed: %s",
@@ -910,17 +925,22 @@ tcp_close_direct(isc_nmsocket_t *sock) {
        REQUIRE(VALID_NMSOCK(sock));
        REQUIRE(sock->tid == isc_nm_tid());
        REQUIRE(sock->type == isc_nm_tcpsocket);
+       isc_nmsocket_t *ssock = sock->server;
 
        if (sock->quota != NULL) {
-               isc_nmsocket_t *ssock = sock->server;
-
                isc_quota_detach(&sock->quota);
-
-               if (ssock->overquota) {
+       }
+       if (ssock != NULL) {
+               ssock->conns--;
+               while (ssock->conns == 0 && ssock->overquota > 0) {
+                       ssock->overquota--;
                        isc_result_t result = accept_connection(ssock);
-                       if (result != ISC_R_QUOTA && result != ISC_R_SOFTQUOTA)
-                       {
-                               ssock->overquota = false;
+                       if (result != ISC_R_SUCCESS) {
+                               isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+                                             ISC_LOGMODULE_NETMGR,
+                                             ISC_LOG_ERROR,
+                                             "TCP connection failed: %s",
+                                             isc_result_totext(result));
                        }
                }
        }

diff --git a/lib/isc/netmgr/uverr2result.c b/lib/isc/netmgr/uverr2result.c
index cf95eba88a4f648e3a61a459e282e049a4da0489..82fa975b8f19aacc3fbfe42b4b1a7edc230c3f97 100644 (file)
--- a/lib/isc/netmgr/uverr2result.c
+++ b/lib/isc/netmgr/uverr2result.c
@@ -37,6 +37,8 @@ isc___nm_uverr2result(int uverr, bool dolog, const char *file,
                return (ISC_R_INVALIDFILE);
        case UV_ENOENT:
                return (ISC_R_FILENOTFOUND);
+       case UV_EAGAIN:
+               return (ISC_R_NOCONN);
        case UV_EACCES:
        case UV_EPERM:
                return (ISC_R_NOPERM);