Implemented ephemeral servers and fixed connection timeout bug (fixes #…

…205) (#206)

* added ephemeral method to server module

* bug fix: connection timeout in server was shorter than expected

* updated client example to use ephemeral server

* bug fix: url -> _url

* bump to version 2.1.2

* bug fix: bad type definition for bugzoo.server.ephemeral

CHANGELOG.md

@@ -1,3 +1,18 @@
+## 2.1.2 (2018-04-30)
+
+### Features
+
+* Added method `bugzoo.server.ephemeral` to allow ephemeral servers to be
+  provisioned. Launches a server and returns a context-bound client that is
+  connected to that server. As soon as the context is closed, the server is
+  safely destroyed.
+
+### Bug Fixes
+
+* Fixed a bug in `bugzoo.client.Client` that caused the connection timeout to
+  abort the connection attempt prematurely.
+
+
 ## 2.1.1 (2018-04-27)
 
 ### Features

bugzoo/client/api.py

@@ -38,10 +38,13 @@ def __init__(self,
 
         # attempt to establish a connection
         url = self._url("status")
-        time_left = float(timeout_connection)
         time_started = timer()
         connected = False
-        while time_left > 0.0 and not connected:
+        while not connected:
+            time_running = timer() - time_started
+            time_left = timeout_connection - time_running
+            if time_left <= 0.0:
+                raise ConnectionFailure
             try:
                 r = requests.get(url, timeout=time_left)
                 connected = r.status_code == 204
@@ -50,9 +53,6 @@ def __init__(self,
             except requests.exceptions.Timeout:
                 raise ConnectionFailure
             time.sleep(0.05)
-            time_left -= timer() - time_started
-        if not connected:
-            raise ConnectionFailure
 
     def _url(self, path: str) -> str:
         """

bugzoo/server/__init__.py

@@ -1,13 +1,18 @@
-from typing import Dict, Any
+from typing import Dict, Any, Iterator
 from functools import wraps
+from contextlib import contextmanager
 import argparse
+import os
+import signal
+import subprocess
 
 import flask
 
 from ..core.bug import Bug
 from ..core.patch import Patch
 from ..manager import BugZoo
 from ..exceptions import *
+from ..client import Client
 
 daemon = None # type: BugZoo
 app = flask.Flask(__name__)
@@ -39,6 +44,37 @@ def wrapper(*args, **kwargs):
     return wrapper
 
 
+@contextmanager
+def ephemeral(*,
+              port: int = 6060,
+              verbose: bool = False
+              ) -> Iterator[Client]:
+    """
+    Launches an ephemeral server instance that will be immediately
+    close when no longer in context.
+
+    Parameters:
+        port: the port that the server should run on.
+        verbose: if set to True, the server will print its output to the
+            stdout, otherwise it will remain silent.
+
+    Returns:
+        a client for communicating with the server.
+    """
+    url = "http://127.0.0.1:{}".format(port)
+    cmd = ["bugzood", "-p", str(port)]
+    try:
+        stdout = None if verbose else subprocess.DEVNULL
+        stderr = None if verbose else subprocess.DEVNULL
+        proc = subprocess.Popen(cmd,
+                                preexec_fn=os.setsid,
+                                stdout=stdout,
+                                stderr=stderr)
+        yield Client(url)
+    finally:
+        os.killpg(proc.pid, signal.SIGTERM)
+
+
 @app.route('/status', methods=['GET'])
 def get_status():
     """

bugzoo/version.py

@@ -1 +1 @@
-__version__ = '2.1.1'
+__version__ = '2.1.2'

examples/client.py

@@ -1,6 +1,6 @@
 import time
 
-import bugzoo.client
+import bugzoo.server
 from bugzoo.core.bug import Bug
 from bugzoo.core.patch import Patch
 
@@ -22,47 +22,47 @@
  BeOpen.com to form the BeOpen PythonLabs team.  In October of the same
 """.lstrip())
 
-client = bugzoo.client.Client(timeout_connection = 90)
-bug = client.bugs['manybugs:python:69223-69224']
-test = bug.harness['p1']
-container = client.containers.provision(bug)
-try:
-    r = client.containers.exec(container, "echo 'hello world'")
-    outcome = client.containers.test(container, test)
-    print(outcome)
+with bugzoo.server.ephemeral() as client:
+    bug = client.bugs['manybugs:python:69223-69224']
+    test = bug.harness['p1']
+    container = client.containers.provision(bug)
+    try:
+        r = client.containers.exec(container, "echo 'hello world'")
+        outcome = client.containers.test(container, test)
+        print(outcome)
 
-    # read a file
-    contents = client.files.read(container, "setup.py")
-    print(contents)
+        # read a file
+        contents = client.files.read(container, "setup.py")
+        print(contents)
 
-    # patch a file
-    outcome = client.containers.patch(container, patch)
-    outcome_text = "yes" if outcome else "no"
-    print("applied patch? {}".format(outcome_text))
+        # patch a file
+        outcome = client.containers.patch(container, patch)
+        outcome_text = "yes" if outcome else "no"
+        print("applied patch? {}".format(outcome_text))
 
-    # get the contents of the patched file
-    contents = client.files.read(container, "LICENSE")
-    print(contents)
+        # get the contents of the patched file
+        contents = client.files.read(container, "LICENSE")
+        print(contents)
 
-    # persist the container
-    client.containers.persist(container, "hulk/foobarblah")
+        # persist the container
+        client.containers.persist(container, "hulk/foobarblah")
 
-    # delete the newly persisted Docker image
-    client.docker.delete_image("hulk/foobarblah")
+        # delete the newly persisted Docker image
+        client.docker.delete_image("hulk/foobarblah")
 
-    # register a mutant
-    mutant = Bug("an-example-bug",
-                 "hulk/foobarblah",
-                 dataset=None,
-                 source=None,
-                 program=bug.program,
-                 source_dir=bug.source_dir,
-                 languages=bug.languages,
-                 harness=bug.harness,
-                 compiler=bug.compiler,
-                 files_to_instrument=bug.files_to_instrument)
-    client.bugs.register(mutant)
-    print("registered mutant")
+        # register a mutant
+        mutant = Bug("an-example-bug",
+                     "hulk/foobarblah",
+                     dataset=None,
+                     source=None,
+                     program=bug.program,
+                     source_dir=bug.source_dir,
+                     languages=bug.languages,
+                     harness=bug.harness,
+                     compiler=bug.compiler,
+                     files_to_instrument=bug.files_to_instrument)
+        client.bugs.register(mutant)
+        print("registered mutant")
 
-finally:
-    del client.containers[container.uid]
+    finally:
+        del client.containers[container.uid]