Setting the newly added compression_level field of
grpc_op::send_initial_metadata by a server now has the effect of
applying that compression level for the subsequent call messages leaving
the server. The ultimate meaning of the level depends on the client's
supported compression algorithms.
Specifically:
Receiving trailing and initial metadata had to be published in
lock-step.
=> If we wanted trailing metadata, we might not get initial metadata processed
until messages arrived.
=> Compression code had no idea what codec to use.
To fix it, publish initial metadata as soon as it's ready (this is a
transport API change).
Requires changes to grpc_call to ensure ordering in processing initial
metadata and messages (one may be delayed).
Exposed at least some bugs in C++ where we never read initial metadata.
I expect at least one more similar bug.
Current latency profiles have their tails dominated by writing latency
logs, which is hugely undesirable.
Now when a thread log fills up, push it to a background thread to write
to disk. At shutdown, wait for all latency traces to be flushed.
Port fling_test to it.
This will be used to:
- port remaining tests to Windows
- enable testing what happens when servers or clients mysteriously disappear