When KORE_MEM_GUARD is set in the environment when Kore is started
it will enable a few memory protection techniques for all kore pools:
1) The metadata is placed away from the actual user pointer returned.
2) Each entry in a pool is placed in such a way that it is followed
immediately by a guard page which has PROT_NONE. Accessing a guard
page will cause an immediate crash.
3) Each entry is marked with PROT_NONE until it is allocated. Once it
is returned to a pool it becomes PROT_NONE again, protecting against
use after frees.
This commit also removes the magic goo from the mem facitilies such
as kore_malloc and friends and moves these as canaries into the kore
pool facilities instead.
Note that using this will increase memory pressure and decrease performance.
It is recommended to enable this during development to catch bugs.
Before we just doubled in size the second we exhausted a pool instead
of doing a more controlled expansion.
Now we will expand at 25% of the initial elm count whenever we need to.
Will help with memory pressure in certain scenarios.
The HTTP layer used to make a copy of each incoming header and its
value for a request. Stop doing that and make HTTP headers zero-copy
all across the board.
This change comes with some api function changes, notably the
http_request_header() function which now takes a const char ** rather
than a char ** out pointer.
This commit also constifies several members of http_request, beware.
Additional rework how the worker processes deal with the accept lock.
Before:
if a worker held the accept lock and it accepted a new connection
it would release the lock for others and back off for 500ms before
attempting to grab the lock again.
This approach worked but under high load this starts becoming obvious.
Now:
- workers not holding the accept lock and not having any connections
will wait less long before returning from kore_platform_event_wait().
- workers not holding the accept lock will no longer blindly wait
an arbitrary amount in kore_platform_event_wait() but will look
at how long until the next lock grab is and base their timeout
on that.
- if a worker its next_lock timeout is up and failed to grab the
lock it will try again in half the time again.
- the worker process holding the lock will when releasing the lock
double check if it still has space for newer connections, if it does
it will keep the lock until it is full. This prevents the lock from
bouncing between several non busy worker processes all the time.
Additional fixes:
- Reduce the number of times we check the timeout list, only do it twice
per second rather then every event tick.
- Fix solo worker count for TLS (we actually hold two processes, not one).
- Make sure we don't accidentally miscalculate the idle time causing new
connections under heavy load to instantly drop.
- Swap from gettimeofday() to clock_gettime() now that MacOS caught up.
This commit adds the ability to use python "await" to suspend
execution of your page handler until the query sent to postgresql
has returned a result.
This is built upon the existing asynchrous query framework Kore had.
With this you can now write stuff like:
async def page(req):
result = await req.pgsql("db", "SELECT name FROM table");
req.response(200, json.dumps(result).encode("utf-8"))
The above code will fire off a query and suspend itself so Kore can
take care of business as usual until the query is successful at which
point Kore will jump back into the handler and resume.
This does not use threading, it's purely based on Python's excellent
coroutines and generators and Kore its built-in pgsql support.
Use CAS to implement primitive spinlock ontop of the pool
if we have been built with TASKS=1.
This allows tasks to safely use kore_malloc() and kore_free()
since those are now backed by pools.
- Change pools to use mmap() for allocating regions.
- Change kore_malloc() to use pools for commonly sized objects.
(split into multiple of 2 buckets, starting at 8 bytes up to 8192).
- Rename kore_mem_free() to kore_free().
The preallocated pools will hold up to 128K of elements per block size.
In case a larger object is to be allocated kore_malloc() will use
malloc() instead.
This basically turns off the HTTP layer for Kore. It does not
compile in anything for HTTP.
This allows Kore to be used as a network application platform as well.
Added an example for this called nohttp.
Other changes that sneaked in while hacking on this:
* Use calloc(), kill pendantic malloc option.
* Killed off SPDY/3.1 support completely, will be superseded by http2
Note that comes with massive changes to a lot of the core API
functions provided by Kore, these might break your application.
Joris Vink
Daniel Fahlgren
Stig Telfer