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id2ctx() routine has been initially implemented for a 2 levels (Processes/Threads) hierarchy, and works fine in this case. However, If we add one (or more) level(s) to the hierarchy, for example: System/Processes/Threads, then id2ctx() will fail. The problem is that id2ctx() (Code pasted below for better understanding) is calling context_find_from_pid(pid, thread), with <thread> argument set to true if given id has a parent. Calling id2ctx() with a Thread ID will work as expected, but calling id2ctx() with a Process ID won't when the process has a parent (System). Here is current code: Context * id2ctx(const char * id) { pid_t parent = 0; pid_t pid = id2pid(id, &parent); if (pid == 0) return NULL; return context_find_from_pid(pid, parent != 0); } A solution to resolve this limitation could be to no longer use <parent> value returned by id2pid(), and to call context_find_from_pid() with thread=false first, if no matching context is found then call it again with thread=true. The other solution would be to allow clients to provide their own implementation of id2ctx().
Created attachment 231970 [details] allow id2ctx() to handle hierarchy with more than 2 levels
The code in the patch would not work: on Linux, a process and main thread in the process have same PID, so id2ctx() would always return the process object instead of the thread. > The other solution would be to allow clients to provide their own implementation of id2ctx(). It is already the case. id2ctx() is intentionally defined in c-header file, clients are supposed to use -I compiler option to pull in a their own version of the header if necessary. I'm changing status to "invalid".
Hi Eugene, (In reply to comment #2) > The code in the patch would not work: on Linux, a process and main thread in > the process have same PID, so id2ctx() would always return the process > object instead of the thread. Right, I missed that point. > > The other solution would be to allow clients to provide their own implementation of id2ctx(). > > It is already the case. id2ctx() is intentionally defined in c-header file, > clients are supposed to use -I compiler option to pull in a their own > version of the header if necessary. Right it works, but adding an #ifdef around id2ctx() would easily allow clients to provide only their own version of id2ctx() without having to duplicate pid-hash.h integrally and potentially have to handle merges of changes that could be made to the original version. > I'm changing status to "invalid". Could you please have a look the 2nd patch I'm submitting? Thanks.
Created attachment 232031 [details] Allow clients to provide user defined version of id2ctx()
I have committed the patch. Thanks!
https://git.eclipse.org/c/tcf/org.eclipse.tcf.agent.git/commit/?h=1.2&id=ce08dcc4685e6fb47c6094155b56f4a107f73430
Comment on attachment 232031 [details] Allow clients to provide user defined version of id2ctx() Marking iplog- since Jean-Michel is correctly tracked as Author in GIT.
