Forward-port the trick to bump up ConnLimit as far as it can

go, but not past MAXCONNECTIONS. Also throw away the FAKE_POLL
caveats since 0.1.0 doesn't need it any more.


svn:r3657

src/common/compat.c

@@ -357,37 +357,51 @@ tor_socketpair(int family, int type, int protocol, int fd[2])
 #endif
 }
 
+#define ULIMIT_BUFFER 32 /* keep 32 extra fd's beyond _ConnLimit */
+
 /** Get the maximum allowed number of file descriptors. (Some systems
  * have a low soft limit.) Make sure we set it to at least
- * <b>required_min</b>. Return 0 if we can, or -1 if we fail. */
-int set_max_file_descriptors(unsigned int required_min) {
+ * <b>*limit</b>. Return a new limit if we can, or -1 if we fail. */
+int set_max_file_descriptors(int limit, int cap) {
 #ifndef HAVE_GETRLIMIT
   log_fn(LOG_INFO,"This platform is missing getrlimit(). Proceeding.");
-  return 0; /* hope we'll be ok */
+  if (limit > cap) {
+    log(LOG_INFO, "ConnLimit must be at most %d. Capping it.", cap);
+    limit = cap;
+  }
 #else
   struct rlimit rlim;
+  int most;
 
   if (getrlimit(RLIMIT_NOFILE, &rlim) != 0) {
     log_fn(LOG_WARN, "Could not get maximum number of file descriptors: %s",
            strerror(errno));
     return -1;
   }
-  if (required_min > rlim.rlim_max) {
-    log_fn(LOG_WARN,"We need %u file descriptors available, and we're limited to %lu. Please change your ulimit.", required_min, (unsigned long int)rlim.rlim_max);
+  if (rlim.rlim_max < limit) {
+    log_fn(LOG_WARN,"We need %d file descriptors available, and we're limited to %lu. Please change your ulimit -n.", limit, (unsigned long int)rlim.rlim_max);
     return -1;
   }
-  if (required_min > rlim.rlim_cur) {
-    log_fn(LOG_INFO,"Raising max file descriptors from %lu to %lu.",
-           (unsigned long int)rlim.rlim_cur, (unsigned long int)rlim.rlim_max);
+  most = ((rlim.rlim_max > cap) ? cap : rlim.rlim_max);
+  if (most > rlim.rlim_cur) {
+    log_fn(LOG_INFO,"Raising max file descriptors from %lu to %d.",
+           (unsigned long int)rlim.rlim_cur, most);
   }
-  rlim.rlim_cur = rlim.rlim_max;
+  rlim.rlim_cur = most;
   if (setrlimit(RLIMIT_NOFILE, &rlim) != 0) {
     log_fn(LOG_WARN, "Could not set maximum number of file descriptors: %s",
            strerror(errno));
     return -1;
   }
-  return 0;
+  /* leave some overhead for logs, etc, */
+  limit = most;
 #endif
+
+  if (limit < ULIMIT_BUFFER) {
+    log_fn(LOG_WARN,"ConnLimit must be at least %d. Failing.", ULIMIT_BUFFER);
+    return -1;
+  }
+  return limit - ULIMIT_BUFFER;
 }
 
 /** Call setuid and setgid to run as <b>user</b>:<b>group</b>.  Return 0 on

src/common/compat.h

@@ -195,7 +195,7 @@ void set_uint16(char *cp, uint16_t v);
 void set_uint32(char *cp, uint32_t v);
 #endif
 
-int set_max_file_descriptors(unsigned int required_min);
+int set_max_file_descriptors(int limit, int cap);
 int switch_id(char *user, char *group);
 #ifdef HAVE_PWD_H
 char *get_user_homedir(const char *username);

src/or/config.c

@@ -64,6 +64,7 @@ static config_abbrev_t config_abbrevs[] = {
   { "BandwidthRateBytes", "BandwidthRate", 0},
   { "BandwidthBurstBytes", "BandwidthBurst", 0},
   { "DirFetchPostPeriod", "StatusFetchPeriod", 0},
+  { "MaxConn", "ConnLimit", 0},
   { NULL, NULL , 0},
 };
 #undef PLURAL
@@ -141,7 +142,7 @@ static config_var_t config_vars[] = {
   VAR("LogLevel",            LINELIST_S, OldLogOptions,      NULL),
   VAR("LogFile",             LINELIST_S, OldLogOptions,      NULL),
   OBSOLETE("LinkPadding"),
-  VAR("MaxConn",             UINT,     MaxConn,              "1024"),
+  VAR("ConnLimit",           UINT,     ConnLimit,            "1024"),
   VAR("MaxOnionsPending",    UINT,     MaxOnionsPending,     "100"),
   VAR("MonthlyAccountingStart",UINT,   _MonthlyAccountingStart,"0"),
   VAR("AccountingMaxKB",     UINT,     _AccountingMaxKB,     "0"),
@@ -312,7 +313,9 @@ options_act(void) {
   close_temp_logs();
   add_callback_log(LOG_NOTICE, LOG_ERR, control_event_logmsg);
 
-  if (set_max_file_descriptors(options->MaxConn) < 0)
+  options->_ConnLimit =
+    set_max_file_descriptors(options->ConnLimit, MAXCONNECTIONS);
+  if (options->_ConnLimit < 0)
     return -1;
 
   {
@@ -1345,16 +1348,6 @@ options_validate(or_options_t *options)
     result = -1;
   }
 
-  if (options->MaxConn < 1) {
-    log(LOG_WARN, "MaxConn option must be a non-zero positive integer.");
-    result = -1;
-  }
-
-  if (options->MaxConn > MAXCONNECTIONS) {
-    log(LOG_WARN, "MaxConn option must be at most %d.", MAXCONNECTIONS);
-    result = -1;
-  }
-
 #define MIN_DIR_FETCH_PERIOD 600
 #define MIN_DIR_POST_PERIOD 300
 #define MIN_REND_POST_PERIOD 300

src/or/main.c

@@ -118,8 +118,8 @@ int connection_add(connection_t *conn) {
   tor_assert(conn);
   tor_assert(conn->s >= 0);
 
-  if (nfds >= get_options()->MaxConn-1) {
-    log_fn(LOG_WARN,"Failing because we have %d connections already. Please set MaxConn higher.", nfds);
+  if (nfds >= get_options()->_ConnLimit-1) {
+    log_fn(LOG_WARN,"Failing because we have %d connections already. Please raise your ulimit -n.", nfds);
     return -1;
   }
 

src/or/or.h

@@ -948,7 +948,8 @@ typedef struct {
   int DirPort; /**< Port to listen on for directory connections. */
   int AuthoritativeDir; /**< Boolean: is this an authoritative directory? */
   int ClientOnly; /**< Boolean: should we never evolve into a server role? */
-  int MaxConn; /**< Maximum number of simultaneous connections. */
+  int ConnLimit; /**< Requested maximum number of simultaneous connections. */
+  int _ConnLimit; /**< Actual maximum number of simultaneous connections. */
   int IgnoreVersion; /**< If true, run no matter what versions of Tor the
                       * directory recommends. */
   int RunAsDaemon; /**< If true, run in the background. (Unix only) */