On Tue, 12 Jan 2021, Luca Olivetti via fpc-pascal wrote:
El 8/1/21 a les 11:14, Luca Olivetti via fpc-pascal ha escrit:
El 8/1/21 a les 11:06, Michael Van Canneyt via fpc-pascal ha escrit:
Are you using https ?
No, plain text http.
An even weirder fact is that I seem to get the wrong ip address (i.e.
the address of a different client).
I think I found the possible cause:
I have an own thread that spawns a TEmbeddedHttpServer (actually a
derived class to manage server-sent-events,
https://lists.lazarus-ide.org/pipermail/lazarus/2020-June/238072.html)
with threaded:=true.
My thread has a method to manage the requests and it does this
FRequest:=ARequest;
Synchronize(@SyncNewConnection);
if FCommandQueue<>nil then .....
I think that, since the method is called from a different thread for
each request, if two requests come at the same time, the FRequest and/or
the FCommandQueue (which is set in the synchronized method) could get
mixed up.
If there is only 1 FRequest instance/location in your thread, then this is
definitely
so...
I now did 2 things:
1) protected that part of the code with a critical section
2) use TThread.Synchronize(nil,..) (since it's not my thread but another one
FCrit.Acquire;
FRequest:=ARequest;
TThread.Synchronize(nil,@SyncNewConnection);
LocCommandQueue:=FCommandQueue;
FCrit.Release;
if LocCommandQueue<>nil then...
WDYT?
From the info you gave me, I think this could work, yes.
Care should be taken that the critical lock does not cause a deadlock,
I don't know what happens in SyncNewConnection.
Am I right thinking that, even if several copies of the above method are
running, each will get it's own local variables, so the LocCommandQueue
variable (as well as the other locals) won't be clobbered by another copy?
Or should I declare them as threadvar?
If FCommandQueue is the only thing that is set during SyncNewConnection
based on TRequest, then yes. For safety, I would Nil the FCommandQueue after
assigning it to locCommandQueue.
Michael.
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