tree ceb3baa07da50457a3642729b0077244489703e9
parent d01e32c3786f2fbbb70c9724a87cf979b4a06232
author Carson Labrado <clabrado@google.com> 1648061415 +0000
committer Ed Tanous <ed@tanous.net> 1652286830 +0000

Refactor HttpClient Class

Refactors HttpClient with the following changes:
- Convert class to singleton
- Replace circular buffers with devectors
- Sending queued requests and closing connections handled
  within their own callback
- Add connection pooling (max size 4)
- HttpClient supports multiple connections to multiple clients
- Retry policies can be set for specific use cases

Also modifies its use in the Subscription class to be compatible
with the refactored code.

It is assumed that a BMC will be able to handle 4 parallel
connections and thus the max pool size is set as 4.  The max
number of queued messages was left unchanged at 50.  Eventually
we may want to allow tuning of these limits to boost performance.
That would come in a future patch.

Tested:
Launched two Event Listener servers that created 6 and 2
subscriptions. Sending a test event created a connection pool
for each server. 4 and 2 connections were added to each pool,
respectively and were used to send the test request. For the first
pool the 2 extra requests were placed into a queue until
connections became available. After a request completed, its
associated connection was used to send the next request in
the queue. Resending the test event caused those prior connections
to be reused instead of new connections being added to the pools.

Signed-off-by: Carson Labrado <clabrado@google.com>
Change-Id: Iba72b3e342cdc05d1fb972e2e9856763a0a1b3c5