Adding upstream version 1.37.1.upstream/1.37.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 269 insertions, 0 deletions

diff --git a/web/server/web_client_cache.c b/web/server/web_client_cache.c
new file mode 100644
index 0000000..1fa5935
--- /dev/null
+++ b/web/server/web_client_cache.c
@@ -0,0 +1,269 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#define WEB_SERVER_INTERNALS 1
+#include "web_client_cache.h"
+
+// ----------------------------------------------------------------------------
+// allocate and free web_clients
+
+#ifdef ENABLE_HTTPS
+
+static void web_client_reuse_ssl(struct web_client *w) {
+    if (netdata_ssl_srv_ctx) {
+        if (w->ssl.conn) {
+            SSL_clear(w->ssl.conn);
+        }
+    }
+}
+#endif
+
+
+static void web_client_zero(struct web_client *w) {
+    // zero everything about it - but keep the buffers
+
+    // remember the pointers to the buffers
+    BUFFER *b1 = w->response.data;
+    BUFFER *b2 = w->response.header;
+    BUFFER *b3 = w->response.header_output;
+
+    // empty the buffers
+    buffer_flush(b1);
+    buffer_flush(b2);
+    buffer_flush(b3);
+
+    freez(w->user_agent);
+
+    // zero everything
+    memset(w, 0, sizeof(struct web_client));
+
+    // restore the pointers of the buffers
+    w->response.data = b1;
+    w->response.header = b2;
+    w->response.header_output = b3;
+}
+
+static void web_client_free(struct web_client *w) {
+    buffer_free(w->response.header_output);
+    buffer_free(w->response.header);
+    buffer_free(w->response.data);
+    freez(w->user_agent);
+#ifdef ENABLE_HTTPS
+    if ((!web_client_check_unix(w)) && (netdata_ssl_srv_ctx)) {
+        if (w->ssl.conn) {
+            SSL_free(w->ssl.conn);
+            w->ssl.conn = NULL;
+        }
+    }
+#endif
+    freez(w);
+}
+
+static struct web_client *web_client_alloc(void) {
+    struct web_client *w = callocz(1, sizeof(struct web_client));
+    w->response.data = buffer_create(NETDATA_WEB_RESPONSE_INITIAL_SIZE);
+    w->response.header = buffer_create(NETDATA_WEB_RESPONSE_HEADER_SIZE);
+    w->response.header_output = buffer_create(NETDATA_WEB_RESPONSE_HEADER_SIZE);
+    return w;
+}
+
+// ----------------------------------------------------------------------------
+// web clients caching
+
+// When clients connect and disconnect, avoid allocating and releasing memory.
+// Instead, when new clients get connected, reuse any memory previously allocated
+// for serving web clients that are now disconnected.
+
+// The size of the cache is adaptive. It caches the structures of 2x
+// the number of currently connected clients.
+
+// Comments per server:
+// SINGLE-THREADED : 1 cache is maintained
+// MULTI-THREADED  : 1 cache is maintained
+// STATIC-THREADED : 1 cache for each thread of the web server
+
+__thread struct clients_cache web_clients_cache = {
+        .pid = 0,
+        .used = NULL,
+        .used_count = 0,
+        .avail = NULL,
+        .avail_count = 0,
+        .allocated = 0,
+        .reused = 0
+};
+
+inline void web_client_cache_verify(int force) {
+#ifdef NETDATA_INTERNAL_CHECKS
+    static __thread size_t count = 0;
+    count++;
+
+    if(unlikely(force || count > 1000)) {
+        count = 0;
+
+        struct web_client *w;
+        size_t used = 0, avail = 0;
+        for(w = web_clients_cache.used; w ; w = w->next) used++;
+        for(w = web_clients_cache.avail; w ; w = w->next) avail++;
+
+        info("web_client_cache has %zu (%zu) used and %zu (%zu) available clients, allocated %zu, reused %zu (hit %zu%%)."
+             , used, web_clients_cache.used_count
+             , avail, web_clients_cache.avail_count
+             , web_clients_cache.allocated
+             , web_clients_cache.reused
+             , (web_clients_cache.allocated + web_clients_cache.reused)?(web_clients_cache.reused * 100 / (web_clients_cache.allocated + web_clients_cache.reused)):0
+        );
+    }
+#else
+    if(unlikely(force)) {
+        info("web_client_cache has %zu used and %zu available clients, allocated %zu, reused %zu (hit %zu%%)."
+             , web_clients_cache.used_count
+             , web_clients_cache.avail_count
+             , web_clients_cache.allocated
+             , web_clients_cache.reused
+             , (web_clients_cache.allocated + web_clients_cache.reused)?(web_clients_cache.reused * 100 / (web_clients_cache.allocated + web_clients_cache.reused)):0
+            );
+    }
+#endif
+}
+
+// destroy the cache and free all the memory it uses
+void web_client_cache_destroy(void) {
+#ifdef NETDATA_INTERNAL_CHECKS
+    if(unlikely(web_clients_cache.pid != 0 && web_clients_cache.pid != gettid()))
+        error("Oops! wrong thread accessing the cache. Expected %d, found %d", (int)web_clients_cache.pid, (int)gettid());
+
+    web_client_cache_verify(1);
+#endif
+
+    netdata_thread_disable_cancelability();
+
+    struct web_client *w, *t;
+
+    w = web_clients_cache.used;
+    while(w) {
+        t = w;
+        w = w->next;
+        web_client_free(t);
+    }
+    web_clients_cache.used = NULL;
+    web_clients_cache.used_count = 0;
+
+    w = web_clients_cache.avail;
+    while(w) {
+        t = w;
+        w = w->next;
+        web_client_free(t);
+    }
+    web_clients_cache.avail = NULL;
+    web_clients_cache.avail_count = 0;
+
+    netdata_thread_enable_cancelability();
+}
+
+struct web_client *web_client_get_from_cache_or_allocate() {
+
+#ifdef NETDATA_INTERNAL_CHECKS
+    if(unlikely(web_clients_cache.pid == 0))
+        web_clients_cache.pid = gettid();
+
+    if(unlikely(web_clients_cache.pid != 0 && web_clients_cache.pid != gettid()))
+        error("Oops! wrong thread accessing the cache. Expected %d, found %d", (int)web_clients_cache.pid, (int)gettid());
+#endif
+
+    netdata_thread_disable_cancelability();
+
+    struct web_client *w = web_clients_cache.avail;
+
+    if(w) {
+        // get it from avail
+        if (w == web_clients_cache.avail) web_clients_cache.avail = w->next;
+        if(w->prev) w->prev->next = w->next;
+        if(w->next) w->next->prev = w->prev;
+        web_clients_cache.avail_count--;
+#ifdef ENABLE_HTTPS
+        web_client_reuse_ssl(w);
+        SSL *ssl = w->ssl.conn;
+#endif
+        web_client_zero(w);
+        web_clients_cache.reused++;
+#ifdef ENABLE_HTTPS
+        w->ssl.conn = ssl;
+        w->ssl.flags = NETDATA_SSL_START;
+        debug(D_WEB_CLIENT_ACCESS,"Reusing SSL structure with (w->ssl = NULL, w->accepted = %u)", w->ssl.flags);
+#endif
+    }
+    else {
+        // allocate it
+        w = web_client_alloc();
+#ifdef ENABLE_HTTPS
+        w->ssl.flags = NETDATA_SSL_START;
+        debug(D_WEB_CLIENT_ACCESS,"Starting SSL structure with (w->ssl = NULL, w->accepted = %u)", w->ssl.flags);
+#endif
+        web_clients_cache.allocated++;
+    }
+
+    // link it to used web clients
+    if (web_clients_cache.used) web_clients_cache.used->prev = w;
+    w->next = web_clients_cache.used;
+    w->prev = NULL;
+    web_clients_cache.used = w;
+    web_clients_cache.used_count++;
+
+    // initialize it
+    w->id = global_statistics_web_client_connected();
+    w->mode = WEB_CLIENT_MODE_NORMAL;
+
+    netdata_thread_enable_cancelability();
+
+    return w;
+}
+
+void web_client_release(struct web_client *w) {
+#ifdef NETDATA_INTERNAL_CHECKS
+    if(unlikely(web_clients_cache.pid != 0 && web_clients_cache.pid != gettid()))
+        error("Oops! wrong thread accessing the cache. Expected %d, found %d", (int)web_clients_cache.pid, (int)gettid());
+
+    if(unlikely(w->running))
+        error("%llu: releasing web client from %s port %s, but it still running.", w->id, w->client_ip, w->client_port);
+#endif
+
+    debug(D_WEB_CLIENT_ACCESS, "%llu: Closing web client from %s port %s.", w->id, w->client_ip, w->client_port);
+
+    web_server_log_connection(w, "DISCONNECTED");
+    web_client_request_done(w);
+    global_statistics_web_client_disconnected();
+
+    netdata_thread_disable_cancelability();
+
+    if(web_server_mode != WEB_SERVER_MODE_STATIC_THREADED) {
+        if (w->ifd != -1) close(w->ifd);
+        if (w->ofd != -1 && w->ofd != w->ifd) close(w->ofd);
+        w->ifd = w->ofd = -1;
+#ifdef ENABLE_HTTPS
+        web_client_reuse_ssl(w);
+        w->ssl.flags = NETDATA_SSL_START;
+#endif
+
+    }
+
+    // unlink it from the used
+    if (w == web_clients_cache.used) web_clients_cache.used = w->next;
+    if(w->prev) w->prev->next = w->next;
+    if(w->next) w->next->prev = w->prev;
+    web_clients_cache.used_count--;
+
+    if(web_clients_cache.avail_count >= 2 * web_clients_cache.used_count) {
+        // we have too many of them - free it
+        web_client_free(w);
+    }
+    else {
+        // link it to the avail
+        if (web_clients_cache.avail) web_clients_cache.avail->prev = w;
+        w->next = web_clients_cache.avail;
+        w->prev = NULL;
+        web_clients_cache.avail = w;
+        web_clients_cache.avail_count++;
+    }
+
+    netdata_thread_enable_cancelability();
+}
+