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| Original file line number | Diff line number | Diff line change |
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@@ -69,3 +69,4 @@ p2venv | |
| test-packaging-venv | ||
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| .vscode/ | ||
| .python-version | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,191 @@ | ||
| import urllib3 | ||
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| from ldclient.config import HTTPConfig | ||
| from ldclient.impl.http import HTTPFactory | ||
| from ldclient.util import throw_if_unsuccessful_response | ||
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| class _BufferedLineReader: | ||
| """ | ||
| Helper class that encapsulates the logic for reading UTF-8 stream data as a series of text lines, | ||
| each of which can be terminated by \n, \r, or \r\n. | ||
| """ | ||
| def lines_from(chunks): | ||
| """ | ||
| Takes an iterable series of encoded chunks (each of "bytes" type) and parses it into an iterable | ||
| series of strings, each of which is one line of text. The line does not include the terminator. | ||
| """ | ||
| last_char_was_cr = False | ||
| partial_line = None | ||
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| for chunk in chunks: | ||
| if len(chunk) == 0: | ||
| continue | ||
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| # bytes.splitlines() will correctly break lines at \n, \r, or \r\n, and is faster than | ||
| # iterating through the characters in Python code. However, we have to adjust the results | ||
| # in several ways as described below. | ||
| lines = chunk.splitlines() | ||
| if last_char_was_cr: | ||
| last_char_was_cr = False | ||
| if chunk[0] == 10: | ||
| # If the last character we saw was \r, and then the first character in buf is \n, then | ||
| # that's just a single \r\n terminator, so we should remove the extra blank line that | ||
| # splitlines added for that first \n. | ||
| lines.pop(0) | ||
| if len(lines) == 0: | ||
| continue # ran out of data, continue to get next chunk | ||
| if partial_line is not None: | ||
| # On our last time through the loop, we ended up with an unterminated line, so we should | ||
| # treat our first parsed line here as a continuation of that. | ||
| lines[0] = partial_line + lines[0] | ||
| partial_line = None | ||
| # Check whether the buffer really ended in a terminator. If it did not, then the last line in | ||
| # lines is a partial line and should not be emitted yet. | ||
| last_char = chunk[len(chunk)-1] | ||
| if last_char == 13: | ||
| last_char_was_cr = True # remember this in case the next chunk starts with \n | ||
| elif last_char != 10: | ||
| partial_line = lines.pop() # remove last element which is the partial line | ||
| for line in lines: | ||
| yield line.decode() | ||
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| class Event: | ||
| """ | ||
| An event received by SSEClient. | ||
| """ | ||
| def __init__(self, event='message', data='', last_event_id=None): | ||
| self._event = event | ||
| self._data = data | ||
| self._id = last_event_id | ||
|
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| @property | ||
| def event(self): | ||
| """ | ||
| The event type, or "message" if not specified. | ||
| """ | ||
| return self._event | ||
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| @property | ||
| def data(self): | ||
| """ | ||
| The event data. | ||
| """ | ||
| return self._data | ||
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| @property | ||
| def last_event_id(self): | ||
| """ | ||
| The last non-empty "id" value received from this stream so far. | ||
| """ | ||
| return self._id | ||
|
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| def dump(self): | ||
| lines = [] | ||
| if self.id: | ||
| lines.append('id: %s' % self.id) | ||
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| # Only include an event line if it's not the default already. | ||
| if self.event != 'message': | ||
| lines.append('event: %s' % self.event) | ||
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| lines.extend('data: %s' % d for d in self.data.split('\n')) | ||
| return '\n'.join(lines) + '\n\n' | ||
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| class SSEClient: | ||
| """ | ||
| A simple Server-Sent Events client. | ||
| This implementation does not include automatic retrying of a dropped connection; the caller will do that. | ||
| If a connection ends, the events iterator will simply end. | ||
| """ | ||
| def __init__(self, url, last_id=None, http_factory=None, **kwargs): | ||
| self.url = url | ||
| self.last_id = last_id | ||
| self._chunk_size = 10000 | ||
|
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| if http_factory is None: | ||
| http_factory = HTTPFactory({}, HTTPConfig()) | ||
| self._timeout = http_factory.timeout | ||
| base_headers = http_factory.base_headers | ||
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| self.http = http_factory.create_pool_manager(1, url) | ||
|
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| # Any extra kwargs will be fed into the request call later. | ||
| self.requests_kwargs = kwargs | ||
|
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| # The SSE spec requires making requests with Cache-Control: nocache | ||
| if 'headers' not in self.requests_kwargs: | ||
| self.requests_kwargs['headers'] = {} | ||
|
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| self.requests_kwargs['headers'].update(base_headers) | ||
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| self.requests_kwargs['headers']['Cache-Control'] = 'no-cache' | ||
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| # The 'Accept' header is not required, but explicit > implicit | ||
| self.requests_kwargs['headers']['Accept'] = 'text/event-stream' | ||
|
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| self._connect() | ||
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| def _connect(self): | ||
| if self.last_id: | ||
| self.requests_kwargs['headers']['Last-Event-ID'] = self.last_id | ||
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| # Use session if set. Otherwise fall back to requests module. | ||
| self.resp = self.http.request( | ||
| 'GET', | ||
| self.url, | ||
| timeout=self._timeout, | ||
| preload_content=False, | ||
| retries=0, # caller is responsible for implementing appropriate retry semantics, e.g. backoff | ||
| **self.requests_kwargs) | ||
|
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| # Raw readlines doesn't work because we may be missing newline characters until the next chunk | ||
| # For some reason, we also need to specify a chunk size because stream=True doesn't seem to guarantee | ||
| # that we get the newlines in a timeline manner | ||
| self.resp_file = self.resp.stream(amt=self._chunk_size) | ||
|
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| # TODO: Ensure we're handling redirects. Might also stick the 'origin' | ||
| # attribute on Events like the Javascript spec requires. | ||
| throw_if_unsuccessful_response(self.resp) | ||
|
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||
| @property | ||
| def events(self): | ||
| """ | ||
| An iterable series of Event objects received from the stream. | ||
| """ | ||
| event_type = "" | ||
| event_data = None | ||
| for line in _BufferedLineReader.lines_from(self.resp_file): | ||
| if line == "": | ||
| if event_data is not None: | ||
| yield Event("message" if event_type == "" else event_type, event_data, self.last_id) | ||
| event_type = "" | ||
| event_data = None | ||
| continue | ||
| colon_pos = line.find(':') | ||
| if colon_pos < 0: | ||
| continue # malformed line - ignore | ||
| if colon_pos == 0: | ||
| continue # comment - currently we're not surfacing these | ||
| name = line[0:colon_pos] | ||
| if colon_pos < (len(line) - 1) and line[colon_pos + 1] == ' ': | ||
| colon_pos += 1 | ||
| value = line[colon_pos+1:] | ||
| if name == 'event': | ||
| event_type = value | ||
| elif name == 'data': | ||
| event_data = value if event_data is None else (event_data + "\n" + value) | ||
| elif name == 'id': | ||
| self.last_id = value | ||
| elif name == 'retry': | ||
| pass # auto-reconnect is not implemented in this simplified client | ||
| # unknown field names are ignored in SSE | ||
|
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| def __enter__(self): | ||
| return self | ||
|
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| def __exit__(self, type, value, traceback): | ||
| self.close() |
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