We do this by creating a new requests.Session object for each request,
sending a "Connection: close" request header, and then explicitly
marking the connection for close after the response is read.
This is to avoid a longstanding race condition with HTTP keepalive
and server timeouts. Due to data processing, capture, etc, requests
may be separated by an arbitrary delay. If this delay is shorter
than the server's KeepAliveTimeout, the same connection is used.
If the delay is longer, a new connection is used. If the delay is
the same, however, the request may be sent on the old connection at
the exact same time that the server closes it. Typically, the
client sees the connection as closing between the request and the
response, which leads to "httplib.BadStatusLine" errors.
This patch avoids the race condition entirely by not using persistent
connections.
Another solution may be to detect those errors and retry the
connection, resending the request. However, the race condition could
potentially show up in other places, like a closed connection during
the request body, not after. Such an error could also be a legitimate
network condition or problem. This solution should be more reliable,
and the overhead of each new connection will hopefully be minimal for
typical workloads.
Added new flag "-R" to command line to perform an automatic removal.
This should be the last of the ways in which a single command could
block the nilmdb thread for a long time.
Enable the following pragmas: synchronous=NORMAL, journal_mode=WAL.
This offers a significant speedup to INSERT times compared to
synchronous=FULL, and is roughly the same as synchronous=OFF
but should be a bit safer.
Things are now block-focused, rather than line-focused. This should
give a pretty big speedup to inserting client data, especially when
inserting preformatted data.
The server buffers the string and passes it to nilmdb. Nilmdb passes
the string to bulkdata. Bulkdata uses the rocket interface to parse
it in chunks, as necessary. Everything gets passed back up and
everyone is happy.
Currently, only pyrocket implements append_string.
This is a pretty big change that will render existing clients unable
to modify the database, but it's important that we use POST or PUT
instead of GET for anything that may change state, in case this
is ever put behind a cache.
These functions can now take an object or a type (class).
If given an object, they will wrap subsequent calls to that object.
If given a type, they will return an object that can be instantiated
to create a new object, and all calls including __init__ will be
covered by the serialization or thread verification.
Previously, we could get empty intervals anyway by having a non-empty
interval and removing a smaller interval around each piece of data.
Turns out that empty intervals are OK and needed in some situations,
so explicitly allow and test for it.
