Fix choose_backend() logic

Author: lsm

apps/load_balancer/Makefile

@@ -1,14 +1,29 @@
+# To build with SSL under windows, do:
+# wine make load_balancer.exe SSL=openssl  # OpenSSL build
+# wine make load_balancer.exe SSL=krypton  # Krypton build
+
 PROG = load_balancer
 SOURCES = $(PROG).c ../../fossa.c
 CFLAGS = -W -Wall -pthread $(CFLAGS_EXTRA)
 
+ifeq ($(SSL), openssl)
+  OPENSSL_PATH = ./openssl-0.9.8
+  CFLAGS_EXTRA += -DNS_ENABLE_SSL -I$(OPENSSL_PATH)/include
+	CFLAGS_EXTRA += /link /libpath:$(OPENSSL_PATH)/lib ssleay32.lib libeay32.lib
+endif
+
+ifeq ($(SSL), krypton)
+	KRYPTON_PATH = ../../../krypton
+  CFLAGS_EXTRA += -DNS_ENABLE_SSL $(KRYPTON_PATH)/krypton.c -I$(KRYPTON_PATH)
+endif
+
 all: $(PROG)
 
 $(PROG): $(SOURCES)
 	$(CC) $(SOURCES) -o $@ $(CFLAGS)
 
 $(PROG).exe: $(SOURCES)
-	cl $(SOURCES) /I.. /MD /Fe$@
+	cl $(SOURCES) /I.. /MD /Fe$@ /DNS_ENABLE_THREADS advapi32.lib $(CFLAGS_EXTRA)
 
 test: $(PROG)
 	$(MAKE) -C ../api_server

apps/load_balancer/load_balancer.c

@@ -52,6 +52,16 @@ static int matches_vhost(const struct ns_str *host, const char *vhost) {
   return host->len == vhost_len && memcmp(host->p, vhost, vhost_len) == 0;
 }
 
+static void write_log(const char *fmt, ...) {
+  va_list ap;
+  if (s_log_file != NULL) {
+    va_start(ap, fmt);
+    vfprintf(s_log_file, fmt, ap);
+    fflush(s_log_file);
+    va_end(ap);
+  }
+}
+
 /*
  * choose_backend parses incoming HTTP request and routes it to the appropriate
  * backend. It assumes that clients don't do HTTP pipelining, handling only
@@ -88,18 +98,17 @@ static void choose_backend(struct ns_connection *nc) {
            /* Prefer most specific URI prefixes */
            strlen(s_http_backends[i].uri_prefix) >
                strlen(s_http_backends[chosen].uri_prefix) ||
-           /* Prefer least used backends  */
-           s_http_backends[i].usage_counter <
-               s_http_backends[chosen].usage_counter)) {
+           /* Among prefixes of the same length chose the least used. */
+           (strlen(s_http_backends[i].uri_prefix) ==
+                strlen(s_http_backends[chosen].uri_prefix) &&
+            s_http_backends[i].usage_counter <
+                s_http_backends[chosen].usage_counter))) {
         chosen = i;
       }
     }
 
-    if (s_log_file != NULL) {
-      fprintf(s_log_file, "%.*s %.*s backend=%d\n", (int) hm.method.len,
-              hm.method.p, (int) hm.uri.len, hm.uri.p, chosen);
-      fflush(s_log_file);
-    }
+    write_log("%.*s %.*s backend=%d\n", (int) hm.method.len, hm.method.p,
+              (int) hm.uri.len, hm.uri.p, chosen);
 
     if (chosen == -1) {
       /* No backend with given uri_prefix found, bail out */
@@ -113,6 +122,8 @@ static void choose_backend(struct ns_connection *nc) {
                     nc->mgr, s_http_backends[chosen].host_port, ev_handler)) ==
                NULL) {
       /* Connection to backend failed */
+      write_log("Connection to [%s] failed\n",
+                s_http_backends[chosen].host_port);
       ns_printf(nc, "%s%s%s\r\n", s_error_500, s_content_len_0,
                 s_connection_close);
     } else {
@@ -206,8 +217,8 @@ static void ev_handler(struct ns_connection *nc, int ev, void *ev_data) {
     case NS_CONNECT:
       if (*(int *) ev_data != 0) {
         /* TODO(lsm): mark backend as defunct, try it later on */
-        fprintf(stderr, "connect(%s) failed\n",
-                s_http_backends[(int) nc->user_data].host_port);
+        write_log("connect(%s) failed\n",
+                  s_http_backends[(int) nc->user_data].host_port);
         ns_printf(nc->proto_data, "%s%s%s\r\n", s_error_500, s_content_len_0,
                   s_connection_close);
       }

platforms/arduino_wifi_CC3000/avrsupport.cpp

@@ -23,17 +23,17 @@ void blink(int times, int ms) {
 }
 
 extern unsigned int __heap_start;
-extern void *__brkval;
+extern void* __brkval;
 
 struct __freelist {
   size_t sz;
-  struct __freelist *nx;
+  struct __freelist* nx;
 };
 
-extern struct __freelist *__flp;
+extern struct __freelist* __flp;
 
 int get_freelistsize() {
-  struct __freelist *current;
+  struct __freelist* current;
   int total = 0;
   for (current = __flp; current; current = current->nx) {
     total += 2;

platforms/arduino_wifi_CC3000/avrsupport.h

@@ -44,10 +44,10 @@ int get_freememsize();
 #endif
 
 #endif /* NS_AVRDEBUG_HEADER_INCLUDED */
-/*
- * Copyright (c) 2015 Cesanta Software Limited
- * All rights reserved
- */
+       /*
+        * Copyright (c) 2015 Cesanta Software Limited
+        * All rights reserved
+        */
 
 #ifndef AVRLIBC_COMPAT_HEADER_INCLUDED
 #define AVRLIBC_COMPAT_HEADER_INCLUDED
@@ -107,10 +107,12 @@ time_t time(time_t* timer);
 #endif
 
 #endif
+
 /*
  * Copyright (c) 2015 Cesanta Software Limited
  * All rights reserved
  */
+
 #ifndef CC3000UTILS_HEADER_INCLUDED
 #define CC3000UTILS_HEADER_INCLUDED