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Viewing changes to grackle/service.py

  • Committer: Aaron Bentley
  • Date: 2012-01-10 10:46:26 UTC
  • Revision ID: aaron@canonical.com-20120110104626-39ehw9nhnzdzggtw
Add README and LICENSE

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__metaclass__ = type
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__all__ = [
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    'ForkedFakeService',
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    'GrackleService',
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    ]
6
 
 
7
 
import httplib
8
 
import logging
9
 
import os
10
 
from signal import SIGKILL
11
 
import simplejson
12
 
import sys
13
 
from wsgiref.headers import Headers
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from wsgiref.simple_server import make_server
15
 
from wsgiref.util import shift_path_info
16
 
 
17
 
from grackle.store import (
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    MemoryStore,
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    )
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21
 
 
22
 
class GrackleService:
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    """A request handler that forwards to an archive store."""
24
 
 
25
 
    def __init__(self, store):
26
 
        self.store = store
27
 
        self.logger = logging.getLogger('http')
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29
 
    def __call__(self, environ, start_response):
30
 
        self.environ = environ
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        self.start_response = start_response
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        self.headers = Headers([('content-type', 'application/json')])
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        self.method = environ['REQUEST_METHOD']
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        if '://' in environ['PATH_INFO']:
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            # All the needed information is embedded in PATH_INFO.
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            shift_path_info(environ)  # shift the host and or port.
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            self.application = shift_path_info(environ)
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            path = environ['PATH_INFO'].split('/')
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            path.pop(0)  # Pop the scheme.
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            self.path = path
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        elif environ['SCRIPT_NAME'] == '':
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            # Remove the application to set the path.
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            self.application = shift_path_info(environ)
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            self.path = environ['PATH_INFO'].split('/')
45
 
        else:
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            self.application = environ['SCRIPT_NAME']
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            self.path = environ['PATH_INFO'].split('/')
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        self.query_string = environ['QUERY_STRING']
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        return self.handle_request()
50
 
 
51
 
    def handle_request(self):
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        """Select the method to handle the request and return a response."""
53
 
        if self.application != 'archive':
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            return self.send_response(httplib.NOT_FOUND)
55
 
        elif self.method == 'PUT':
56
 
            return self.do_PUT()
57
 
        elif self.method == 'POST':
58
 
            return self.do_POST()
59
 
        elif self.method == 'GET':
60
 
            return self.do_GET()
61
 
        return self.send_response(httplib.METHOD_NOT_ALLOWED)
62
 
 
63
 
    def send_response(self, code, response='', reason=None):
64
 
        """Set the status code and reason, then return the response."""
65
 
        if reason is None:
66
 
            reason = httplib.responses[code]
67
 
        response_status = '%s %s' % (code, reason)
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        self.start_response(response_status, self.headers.items())
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        return [response]
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71
 
    def do_PUT(self):
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        """Create an archive or message on PUT."""
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        if len(self.path) == 1:
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            # This expected path is /archive/archive_id.
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            try:
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                self.store.put_archive(self.path[0])
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                return self.send_response(httplib.CREATED)
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            except Exception, error:
79
 
                return self.send_response(
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                    httplib.BAD_REQUEST, reason=error.__doc__)
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        elif len(self.path) == 2:
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            # This expected path is /archive/archive_id/message_id.
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            try:
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                put_input = self.environ['wsgi.input']
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                message = put_input.read(int(self.environ['CONTENT_LENGTH']))
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                self.store.put_message(self.path[0], self.path[1], message)
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                return self.send_response(httplib.CREATED)
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            except Exception, error:
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                return self.send_response(
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                    httplib.BAD_REQUEST, reason=error.__doc__)
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92
 
    def do_POST(self):
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        """Change a message on POST."""
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        if len(self.path) == 2:
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            # This expected path is /archive/archive_id/message_id.
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            try:
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                # This expected path is /archive/archive_id/message_id.
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                response = self.store.hide_message(
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                    self.path[0], self.path[1], self.query_string)
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                response = simplejson.dumps(response)
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                return self.send_response(httplib.OK, response=response)
102
 
            except Exception, error:
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                return self.send_response(
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                    httplib.BAD_REQUEST, reason=error.__doc__)
105
 
 
106
 
    def do_GET(self):
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        """Retrieve a list of messages on GET."""
108
 
        try:
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            response = self.store.get_messages(
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                self.path[0], self.query_string)
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            response = simplejson.dumps(response)
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            return self.send_response(httplib.OK, response=response)
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        except Exception, error:
114
 
            return self.send_response(
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                httplib.BAD_REQUEST, reason=error.__doc__)
116
 
 
117
 
    def log_message(self, format, *args):
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        """Override log_message to use standard Python logging."""
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        message = "%s - - [%s] %s\n" % (
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            self.address_string(), self.log_date_time_string(), format % args)
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        self.logger.info(message)
122
 
 
123
 
 
124
 
class ForkedFakeService:
125
 
    """A Grackle service fake, as a ContextManager."""
126
 
 
127
 
    def __init__(self, port, message_archives=None, write_logs=False):
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        """Constructor.
129
 
 
130
 
        :param port: The tcp port to use.
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        :param message_archives: A dict of lists of dicts representing
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            archives of messages. The outer dict represents the archive,
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            the list represents the list of messages for that archive.
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        :param write_logs: If true, log messages will be written to stdout.
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        """
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        self.pid = None
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        self.port = port
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        if message_archives is None:
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            self.message_archives = {}
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        else:
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            self.message_archives = message_archives
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        self.read_end, self.write_end = os.pipe()
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        self.write_logs = write_logs
144
 
 
145
 
    @staticmethod
146
 
    def from_client(client, message_archives=None):
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        """Instantiate a ForkedFakeService from the client.
148
 
 
149
 
        :param port: The client to provide service for.
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        :param message_archives: A dict of lists of dicts representing
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            archives of messages. The outer dict represents the archive,
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            the list represents the list of messages for that archive.
153
 
        """
154
 
        return ForkedFakeService(client.port, message_archives)
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156
 
    def is_ready(self):
157
 
        """Tell the parent process that the server is ready for writes."""
158
 
        os.write(self.write_end, 'asdf')
159
 
 
160
 
    def __enter__(self):
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        """Run the service.
162
 
 
163
 
        Fork and start a server in the child.  Return when the server is ready
164
 
        for use."""
165
 
        pid = os.fork()
166
 
        if pid == 0:
167
 
            self.start_server()
168
 
        self.pid = pid
169
 
        os.read(self.read_end, 1)
170
 
        return
171
 
 
172
 
    def start_server(self):
173
 
        """Start the HTTP server."""
174
 
        app = GrackleService(MemoryStore(self.message_archives))
175
 
        service = make_server('', self.port, app)
176
 
        self.is_ready()
177
 
        if self.write_logs:
178
 
            logging.basicConfig(
179
 
                stream=sys.stderr, level=logging.INFO)
180
 
        service.serve_forever()
181
 
 
182
 
    def __exit__(self, exc_type, exc_val, traceback):
183
 
        os.kill(self.pid, SIGKILL)
184
 
 
185
 
 
186
 
if __name__ == '__main__':
187
 
    app = GrackleService(MemoryStore({}))
188
 
    service = make_server('', 8787, app)
189
 
    service.serve_forever()