Merge pull request #182 from zhenlineo/1.5-max-pool-size

Max connection pool size

Author: zhenlineo

neo4j/bolt/connection.py

@@ -32,22 +32,27 @@
 from select import select
 from socket import socket, SOL_SOCKET, SO_KEEPALIVE, SHUT_RDWR, error as SocketError, timeout as SocketTimeout, AF_INET, AF_INET6
 from struct import pack as struct_pack, unpack as struct_unpack
-from threading import RLock
+from threading import RLock, Condition
 
 from neo4j.addressing import SocketAddress, is_ip_address
 from neo4j.bolt.cert import KNOWN_HOSTS
 from neo4j.bolt.response import InitResponse, AckFailureResponse, ResetResponse
 from neo4j.compat.ssl import SSL_AVAILABLE, HAS_SNI, SSLError
-from neo4j.exceptions import ProtocolError, SecurityError, ServiceUnavailable
+from neo4j.exceptions import ClientError, ProtocolError, SecurityError, ServiceUnavailable
 from neo4j.meta import version
 from neo4j.packstream import Packer, Unpacker
 from neo4j.util import import_best as _import_best
+from time import clock
 
 ChunkedInputBuffer = _import_best("neo4j.bolt._io", "neo4j.bolt.io").ChunkedInputBuffer
 ChunkedOutputBuffer = _import_best("neo4j.bolt._io", "neo4j.bolt.io").ChunkedOutputBuffer
 
 
+INFINITE = -1
+DEFAULT_MAX_CONNECTION_LIFETIME = INFINITE
+DEFAULT_MAX_CONNECTION_POOL_SIZE = INFINITE
 DEFAULT_CONNECTION_TIMEOUT = 5.0
+DEFAULT_CONNECTION_ACQUISITION_TIMEOUT = 60
 DEFAULT_PORT = 7687
 DEFAULT_USER_AGENT = "neo4j-python/%s" % version
 
@@ -178,6 +183,8 @@ def __init__(self, address, sock, error_handler, **config):
         self.packer = Packer(self.output_buffer)
         self.unpacker = Unpacker()
         self.responses = deque()
+        self._max_connection_lifetime = config.get("max_connection_lifetime", DEFAULT_MAX_CONNECTION_LIFETIME)
+        self._creation_timestamp = clock()
 
         # Determine the user agent and ensure it is a Unicode value
         user_agent = config.get("user_agent", DEFAULT_USER_AGENT)
@@ -201,6 +208,7 @@ def __init__(self, address, sock, error_handler, **config):
         # Pick up the server certificate, if any
         self.der_encoded_server_certificate = config.get("der_encoded_server_certificate")
 
+    def Init(self):
         response = InitResponse(self)
         self.append(INIT, (self.user_agent, self.auth_dict), response=response)
         self.sync()
@@ -360,6 +368,9 @@ def _unpack(self):
                 more = False
         return details, summary_signature, summary_metadata
 
+    def timedout(self):
+        return 0 <= self._max_connection_lifetime <= clock() - self._creation_timestamp
+
     def sync(self):
         """ Send and fetch all outstanding messages.
 
@@ -396,11 +407,14 @@ class ConnectionPool(object):
 
     _closed = False
 
-    def __init__(self, connector, connection_error_handler):
+    def __init__(self, connector, connection_error_handler, **config):
         self.connector = connector
         self.connection_error_handler = connection_error_handler
         self.connections = {}
         self.lock = RLock()
+        self.cond = Condition(self.lock)
+        self._max_connection_pool_size = config.get("max_connection_pool_size", DEFAULT_MAX_CONNECTION_POOL_SIZE)
+        self._connection_acquisition_timeout = config.get("connection_acquisition_timeout", DEFAULT_CONNECTION_ACQUISITION_TIMEOUT)
 
     def __enter__(self):
         return self
@@ -424,23 +438,42 @@ def acquire_direct(self, address):
                 connections = self.connections[address]
             except KeyError:
                 connections = self.connections[address] = deque()
-            for connection in list(connections):
-                if connection.closed() or connection.defunct():
-                    connections.remove(connection)
-                    continue
-                if not connection.in_use:
-                    connection.in_use = True
-                    return connection
-            try:
-                connection = self.connector(address, self.connection_error_handler)
-            except ServiceUnavailable:
-                self.remove(address)
-                raise
-            else:
-                connection.pool = self
-                connection.in_use = True
-                connections.append(connection)
-                return connection
+
+            connection_acquisition_start_timestamp = clock()
+            while True:
+                # try to find a free connection in pool
+                for connection in list(connections):
+                    if connection.closed() or connection.defunct() or connection.timedout():
+                        connections.remove(connection)
+                        continue
+                    if not connection.in_use:
+                        connection.in_use = True
+                        return connection
+                # all connections in pool are in-use
+                can_create_new_connection = self._max_connection_pool_size == INFINITE or len(connections) < self._max_connection_pool_size
+                if can_create_new_connection:
+                    try:
+                        connection = self.connector(address, self.connection_error_handler)
+                    except ServiceUnavailable:
+                        self.remove(address)
+                        raise
+                    else:
+                        connection.pool = self
+                        connection.in_use = True
+                        connections.append(connection)
+                        return connection
+
+                # failed to obtain a connection from pool because the pool is full and no free connection in the pool
+                span_timeout = self._connection_acquisition_timeout - (clock() - connection_acquisition_start_timestamp)
+                if span_timeout > 0:
+                    self.cond.wait(span_timeout)
+                    # if timed out, then we throw error. This time computation is needed, as with python 2.7, we cannot
+                    # tell if the condition is notified or timed out when we come to this line
+                    if self._connection_acquisition_timeout <= (clock() - connection_acquisition_start_timestamp):
+                        raise ClientError("Failed to obtain a connection from pool within {!r}s".format(
+                            self._connection_acquisition_timeout))
+                else:
+                    raise ClientError("Failed to obtain a connection from pool within {!r}s".format(self._connection_acquisition_timeout))
 
     def acquire(self, access_mode=None):
         """ Acquire a connection to a server that can satisfy a set of parameters.
@@ -454,6 +487,7 @@ def release(self, connection):
         """
         with self.lock:
             connection.in_use = False
+            self.cond.notify_all()
 
     def in_use_connection_count(self, address):
         """ Count the number of connections currently in use to a given
@@ -600,8 +634,10 @@ def connect(address, ssl_context=None, error_handler=None, **config):
         s.shutdown(SHUT_RDWR)
         s.close()
     elif agreed_version == 1:
-        return Connection(address, s, der_encoded_server_certificate=der_encoded_server_certificate,
+        connection = Connection(address, s, der_encoded_server_certificate=der_encoded_server_certificate,
                           error_handler=error_handler, **config)
+        connection.Init()
+        return connection
     elif agreed_version == 0x48545450:
         log_error("S: [CLOSE]")
         s.close()

neo4j/v1/__init__.py

@@ -18,9 +18,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
-from neo4j.exceptions import *
-
 from .api import *
 from .direct import *
 from .exceptions import *

neo4j/v1/api.py

@@ -25,8 +25,8 @@
 from time import time, sleep
 from warnings import warn
 
-from neo4j.bolt import ProtocolError, ServiceUnavailable
-from neo4j.compat import unicode, urlparse
+from neo4j.exceptions import ProtocolError, ServiceUnavailable
+from neo4j.compat import urlparse
 from neo4j.exceptions import CypherError, TransientError
 
 from .exceptions import DriverError, SessionError, SessionExpired, TransactionError

neo4j/v1/direct.py

@@ -20,7 +20,7 @@
 
 
 from neo4j.addressing import SocketAddress, resolve
-from neo4j.bolt import DEFAULT_PORT, ConnectionPool, connect, ConnectionErrorHandler
+from neo4j.bolt.connection import DEFAULT_PORT, ConnectionPool, connect, ConnectionErrorHandler
 from neo4j.exceptions import ServiceUnavailable
 from neo4j.v1.api import Driver
 from neo4j.v1.security import SecurityPlan
@@ -37,8 +37,8 @@ def __init__(self):
 
 class DirectConnectionPool(ConnectionPool):
 
-    def __init__(self, connector, address):
-        super(DirectConnectionPool, self).__init__(connector, DirectConnectionErrorHandler())
+    def __init__(self, connector, address, **config):
+        super(DirectConnectionPool, self).__init__(connector, DirectConnectionErrorHandler(), **config)
         self.address = address
 
     def acquire(self, access_mode=None):
@@ -73,7 +73,7 @@ def __init__(self, uri, **config):
         def connector(address, error_handler):
             return connect(address, security_plan.ssl_context, error_handler, **config)
 
-        pool = DirectConnectionPool(connector, self.address)
+        pool = DirectConnectionPool(connector, self.address, **config)
         pool.release(pool.acquire())
         Driver.__init__(self, pool, **config)
 

neo4j/v1/routing.py

@@ -34,7 +34,7 @@
 
 LOAD_BALANCING_STRATEGY_LEAST_CONNECTED = 0
 LOAD_BALANCING_STRATEGY_ROUND_ROBIN = 1
-LOAD_BALANCING_STRATEGY_DEFAULT = LOAD_BALANCING_STRATEGY_LEAST_CONNECTED
+DEFAULT_LOAD_BALANCING_STRATEGY = LOAD_BALANCING_STRATEGY_LEAST_CONNECTED
 
 
 class OrderedSet(MutableSet):
@@ -166,7 +166,7 @@ class LoadBalancingStrategy(object):
 
     @classmethod
     def build(cls, connection_pool, **config):
-        load_balancing_strategy = config.get("load_balancing_strategy", LOAD_BALANCING_STRATEGY_DEFAULT)
+        load_balancing_strategy = config.get("load_balancing_strategy", DEFAULT_LOAD_BALANCING_STRATEGY)
         if load_balancing_strategy == LOAD_BALANCING_STRATEGY_LEAST_CONNECTED:
             return LeastConnectedLoadBalancingStrategy(connection_pool)
         elif load_balancing_strategy == LOAD_BALANCING_STRATEGY_ROUND_ROBIN:
@@ -265,7 +265,7 @@ class RoutingConnectionPool(ConnectionPool):
     """
 
     def __init__(self, connector, initial_address, routing_context, *routers, **config):
-        super(RoutingConnectionPool, self).__init__(connector, RoutingConnectionErrorHandler(self))
+        super(RoutingConnectionPool, self).__init__(connector, RoutingConnectionErrorHandler(self), **config)
         self.initial_address = initial_address
         self.routing_context = routing_context
         self.routing_table = RoutingTable(routers)

test/integration/test_driver.py

@@ -19,8 +19,8 @@
 # limitations under the License.
 
 
-from neo4j.v1 import GraphDatabase, ProtocolError, ServiceUnavailable
-
+from neo4j.v1 import GraphDatabase, ServiceUnavailable
+from neo4j.exceptions import ProtocolError
 from test.integration.tools import IntegrationTestCase
 
 

test/integration/test_security.py

@@ -23,7 +23,8 @@
 from ssl import SSLSocket
 from unittest import skipUnless
 
-from neo4j.v1 import GraphDatabase, SSL_AVAILABLE, TRUST_ON_FIRST_USE, TRUST_CUSTOM_CA_SIGNED_CERTIFICATES, AuthError
+from neo4j.v1 import GraphDatabase, SSL_AVAILABLE, TRUST_ON_FIRST_USE, TRUST_CUSTOM_CA_SIGNED_CERTIFICATES
+from neo4j.exceptions import AuthError
 
 from test.integration.tools import IntegrationTestCase
 

test/integration/test_session.py

@@ -24,7 +24,8 @@
 from neo4j.v1 import \
     READ_ACCESS, WRITE_ACCESS, \
     CypherError, SessionError, TransactionError, \
-    Node, Relationship, Path, CypherSyntaxError
+    Node, Relationship, Path
+from neo4j.exceptions import CypherSyntaxError
 
 from test.integration.tools import DirectIntegrationTestCase
 

test/integration/tools.py

@@ -32,7 +32,8 @@
 
 from boltkit.controller import WindowsController, UnixController
 
-from neo4j.v1 import GraphDatabase, AuthError
+from neo4j.v1 import GraphDatabase
+from neo4j.exceptions import AuthError
 from neo4j.util import ServerVersion
 
 from test.env import NEO4J_SERVER_PACKAGE, NEO4J_USER, NEO4J_PASSWORD

test/performance/tools.py

@@ -34,7 +34,8 @@
 
 from boltkit.controller import WindowsController, UnixController
 
-from neo4j.v1 import GraphDatabase, AuthError
+from neo4j.v1 import GraphDatabase
+from neo4j.exceptions import AuthError
 from neo4j.util import ServerVersion
 
 from test.env import NEO4J_SERVER_PACKAGE, NEO4J_USER, NEO4J_PASSWORD