Fix: Duplicate UUIDs generated in forked processes

Author: Michael Penick

ext/php_cassandra.c

@@ -273,7 +273,8 @@ static PHP_GINIT_FUNCTION(cassandra)
 {
   uv_once(&log_once, php_cassandra_log_initialize);
 
-  cassandra_globals->uuid_gen            = cass_uuid_gen_new();
+  cassandra_globals->uuid_gen            = NULL;
+  cassandra_globals->uuid_gen_pid        = 0;
   cassandra_globals->persistent_clusters = 0;
   cassandra_globals->persistent_sessions = 0;
   PHP5TO7_ZVAL_UNDEF(cassandra_globals->type_varchar);
@@ -297,7 +298,9 @@ static PHP_GINIT_FUNCTION(cassandra)
 
 static PHP_GSHUTDOWN_FUNCTION(cassandra)
 {
-  cass_uuid_gen_free(cassandra_globals->uuid_gen);
+  if (cassandra_globals->uuid_gen) {
+    cass_uuid_gen_free(cassandra_globals->uuid_gen);
+  }
   php_cassandra_log_cleanup();
 }
 

ext/php_cassandra.h

@@ -38,6 +38,19 @@
 #include <Zend/zend_exceptions.h>
 #include <Zend/zend_interfaces.h>
 
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef PHP_WIN32
+typedef int pid_t;
+#include <process.h>
+#endif
+
 #if PHP_VERSION_ID < 50304
 #  error PHP 5.3.4 or later is required in order to build the driver
 #endif
@@ -478,6 +491,7 @@ PHP_MINFO_FUNCTION(cassandra);
 
 ZEND_BEGIN_MODULE_GLOBALS(cassandra)
   CassUuidGen          *uuid_gen;
+  pid_t                 uuid_gen_pid;
   unsigned int          persistent_clusters;
   unsigned int          persistent_sessions;
   php5to7_zval          type_varchar;

ext/util/uuid_gen.c

@@ -20,20 +20,40 @@
 
 ZEND_EXTERN_MODULE_GLOBALS(cassandra)
 
+static CassUuidGen* get_uuid_gen() {
+  /* Create a new uuid generator if our PID has changed. This prevents the same
+   * UUIDs from being generated in forked processes.
+   */
+  if (CASSANDRA_G(uuid_gen_pid) != getpid()) {
+    if (CASSANDRA_G(uuid_gen)) {
+      cass_uuid_gen_free(CASSANDRA_G(uuid_gen));
+    }
+    CASSANDRA_G(uuid_gen) = cass_uuid_gen_new();
+    CASSANDRA_G(uuid_gen_pid) = getpid();
+  }
+  return CASSANDRA_G(uuid_gen);
+}
+
 void
 php_cassandra_uuid_generate_random(CassUuid *out TSRMLS_DC)
 {
-  cass_uuid_gen_random(CASSANDRA_G(uuid_gen), out);
+  CassUuidGen* uuid_gen = get_uuid_gen(); 
+  if (!uuid_gen) return;
+  cass_uuid_gen_random(uuid_gen, out);
 }
 
 void
 php_cassandra_uuid_generate_time(CassUuid *out TSRMLS_DC)
 {
-  cass_uuid_gen_time(CASSANDRA_G(uuid_gen), out);
+  CassUuidGen* uuid_gen = get_uuid_gen(); 
+  if (!uuid_gen) return;
+  cass_uuid_gen_time(uuid_gen, out);
 }
 
 void
 php_cassandra_uuid_generate_from_time(long timestamp, CassUuid *out TSRMLS_DC)
 {
-  cass_uuid_gen_from_time(CASSANDRA_G(uuid_gen), (cass_uint64_t) timestamp, out);
+  CassUuidGen* uuid_gen = get_uuid_gen(); 
+  if (!uuid_gen) return;
+  cass_uuid_gen_from_time(uuid_gen, (cass_uint64_t) timestamp, out);
 }