Implementing this Was harder than I first expected. The basic idea is as
follows: The master process puts each message arriving from a client that
isn't "canceltiles" into a (client-specific) queue. A separate thread that
pulls messages from the queue at its own pace and handles them as
before. Incoming "canceltiles" messages are handled specially, though: The
queue is emptied of "tile" messages.
The above sounds simple but there are several details that were a bit tricky
to get right.
Otherwise, if we use the same port number and same HTTPServer, if enough
clients try to contact us and, we won't be able to accept child processes
having been spawned.
Also add some temporary debugging output here and there to debug lifecycle
management issues.
Works now for the trivial 'connect' test program. Still need to add
pre-spawning of a new child process as soon as an existing one from the pool
has been taking into use. And need to test with the actual JS client.
Add a new program, loadtest, that runs a requested number of client sessions
in parallel to a loolwsd server. A client session loads one of a list of test
documents, and does some operations on it.
Move the getTokenInteger() and getTokenString() functions out from LOOLSession
into a new namespace LOOLProtocol, as they are neeeded also in the loadtest
program.
Add, also in LOOLProtocol, functions to parse some of the messages from the
server. (In general that is done in client JavaScript code, of course; only
for testing purposes needed in C++ code.)
