Merge branch 'branch_limit_test' of https://github.com/Rozelette/compose into Rozelette-branch_limit_test

Signed-off-by: Joffrey F <joffrey@docker.com>

compose/cli/command.py

@@ -99,8 +99,13 @@ def get_project(project_dir, config_path=None, project_name=None, verbose=False,
         host=host, environment=environment
     )
 
+    global_parallel_limit = environment.get('COMPOSE_PARALLEL_LIMIT')
+    if global_parallel_limit:
+        global_parallel_limit = int(global_parallel_limit)
+
     with errors.handle_connection_errors(client):
-        return Project.from_config(project_name, config_data, client)
+        return Project.from_config(project_name, config_data, client,
+                                   global_parallel_limit=global_parallel_limit)
 
 
 def get_project_name(working_dir, project_name=None, environment=None):

compose/const.py

@@ -18,6 +18,7 @@ LABEL_VERSION = 'com.docker.compose.version'
 LABEL_VOLUME = 'com.docker.compose.volume'
 LABEL_CONFIG_HASH = 'com.docker.compose.config-hash'
 NANOCPUS_SCALE = 1000000000
+PARALLEL_LIMIT = 64
 
 SECRETS_PATH = '/run/secrets'
 

compose/parallel.py

@@ -15,6 +15,7 @@ from six.moves.queue import Queue
 from compose.cli.colors import green
 from compose.cli.colors import red
 from compose.cli.signals import ShutdownException
+from compose.const import PARALLEL_LIMIT
 from compose.errors import HealthCheckFailed
 from compose.errors import NoHealthCheckConfigured
 from compose.errors import OperationFailedError
@@ -26,6 +27,19 @@ log = logging.getLogger(__name__)
 STOP = object()
 
 
+class GlobalLimit(object):
+    """Simple class to hold a global semaphore limiter for a project. This class
+    should be treated as a singleton that is instantiated when the project is.
+    """
+
+    global_limiter = Semaphore(PARALLEL_LIMIT)
+
+    @classmethod
+    def set_global_limit(cls, value=None):
+        if value is not None:
+            cls.global_limiter = Semaphore(value)
+
+
 def parallel_execute(objects, func, get_name, msg, get_deps=None, limit=None, parent_objects=None):
     """Runs func on objects in parallel while ensuring that func is
     ran on object only after it is ran on all its dependencies.
@@ -173,7 +187,7 @@ def producer(obj, func, results, limiter):
     The entry point for a producer thread which runs func on a single object.
     Places a tuple on the results queue once func has either returned or raised.
     """
-    with limiter:
+    with limiter, GlobalLimit.global_limiter:
         try:
             result = func(obj)
             results.put((obj, result, None))

compose/project.py

@@ -61,13 +61,15 @@ class Project(object):
     """
     A collection of services.
     """
-    def __init__(self, name, services, client, networks=None, volumes=None, config_version=None):
+    def __init__(self, name, services, client, networks=None, volumes=None, config_version=None,
+                 parallel_limit=None):
         self.name = name
         self.services = services
         self.client = client
         self.volumes = volumes or ProjectVolumes({})
         self.networks = networks or ProjectNetworks({}, False)
         self.config_version = config_version
+        parallel.GlobalLimit.set_global_limit(value=parallel_limit)
 
     def labels(self, one_off=OneOffFilter.exclude):
         labels = ['{0}={1}'.format(LABEL_PROJECT, self.name)]
@@ -76,7 +78,7 @@ class Project(object):
         return labels
 
     @classmethod
-    def from_config(cls, name, config_data, client):
+    def from_config(cls, name, config_data, client, global_parallel_limit=None):
         """
         Construct a Project from a config.Config object.
         """
@@ -87,7 +89,8 @@ class Project(object):
             networks,
             use_networking)
         volumes = ProjectVolumes.from_config(name, config_data, client)
-        project = cls(name, [], client, project_networks, volumes, config_data.version)
+        project = cls(name, [], client, project_networks, volumes, config_data.version,
+                      parallel_limit=global_parallel_limit)
 
         for service_dict in config_data.services:
             service_dict = dict(service_dict)

tests/unit/parallel_test.py

@@ -6,6 +6,7 @@ from threading import Lock
 import six
 from docker.errors import APIError
 
+from compose.parallel import GlobalLimit
 from compose.parallel import parallel_execute
 from compose.parallel import parallel_execute_iter
 from compose.parallel import ParallelStreamWriter
@@ -67,6 +68,29 @@ def test_parallel_execute_with_limit():
     assert errors == {}
 
 
+def test_parallel_execute_with_global_limit():
+    GlobalLimit.set_global_limit(1)
+    tasks = 20
+    lock = Lock()
+
+    def f(obj):
+        locked = lock.acquire(False)
+        # we should always get the lock because we're the only thread running
+        assert locked
+        lock.release()
+        return None
+
+    results, errors = parallel_execute(
+        objects=list(range(tasks)),
+        func=f,
+        get_name=six.text_type,
+        msg="Testing",
+    )
+
+    assert results == tasks * [None]
+    assert errors == {}
+
+
 def test_parallel_execute_with_deps():
     log = []