/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */ /* * This file is part of the LibreOffice project. * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ // Helper to reduce parallelism, specifically for msi installset packaging // // Ideally it would hook into make's jobserver, but it is too easy to deadlock the build at the // packaging stage (all jobs are started at once, consuming all available slots as part of general // parallelism, and then each job waiting for an additional job token but since all jobs are in // waiting stage: you have a deadlock). // That in turn is an advantage for a simple approach with separate lock and release commands, since // everything is started at once, and all jobs that will be queued are all jobs that use the helper, // there will be jobs in waiting state and keeping the semaphore active as long as it matters. #include #include using namespace std; int grab(HANDLE& semaphore_handle) { DWORD waitresult = WaitForSingleObject(semaphore_handle, INFINITE); switch (waitresult) { case WAIT_OBJECT_0: return 0; case WAIT_TIMEOUT: fprintf(stderr, "grabbing a slot failed with timeout despite waiting for INFINITE?\n"); break; case WAIT_FAILED: fprintf(stderr, "grabbing a slot failed with error: %d\n", GetLastError()); break; default: fprintf(stderr, "grabbing a slot failed with status %d - error %d", waitresult, GetLastError()); } return 1; } int release(HANDLE& semaphore_handle) { if (ReleaseSemaphore(semaphore_handle, 1, NULL)) { return 0; } else { fprintf(stderr, "something went wrong trying to release a slot: %d\n", GetLastError()); return 1; } } int wmain(int argc, wchar_t* argv[]) { if (argc != 2) { fprintf(stderr, "Invalid number of arguments!\n"); fprintf(stderr, "call with 'grab' or 'release'\n"); exit(1); } // since the reason for limiting the parallelism is the instability with cscript/WiLangId.vbs // calls and high parallelism, not having that unique/potentially sharing the limit semaphore // with another build is not a problem but considered a feature... LPCWSTR semaphorename = L"lo_installset_limiter"; HANDLE semaphore_handle = OpenSemaphoreW(SYNCHRONIZE | SEMAPHORE_MODIFY_STATE, false, semaphorename); if (semaphore_handle == NULL) { fprintf(stdout, "no existing semaphore, creating new one\n"); // Need to have a buffer slot, since the helper isn't persistent. // When it is called to release a slot it might be that all holders of the semaphore // are gone already and thus the semaphore also gets closed and is no longer present on the // system. So when it creates a new one to use, and then releases one it would hit the max // limit otherwise. This only happens when nothing else is waiting for a slot anymore, // i.e. when there are already fewer jobs than imposed by the limiter. // A limit of four (main installer and 3 controlled by this limiter) was chosen because that // won't affect overall build time (creating the main installer with multiple languages // takes much longer than all the helppackages and the single sdk package combined, even // when those are limited to three jobs), and seems to be low enough to avoid the random // cscript/WiLangId.vbs failures. semaphore_handle = CreateSemaphoreW(NULL, 3, 4, semaphorename); // keep this process alive for other jobs to grab the semaphore, otherwise it is gone too // quickly and everything creates their own semaphore that immediately has enough slots, // completely bypassing the point of having a limiter... Sleep(500); } if (semaphore_handle == NULL) { fprintf(stderr, "Error creating/opening the semaphore - bailing out (%d)\n", GetLastError()); exit(1); } if (wcscmp(argv[1], L"grab") == 0) { exit(grab(semaphore_handle)); } else if (wcscmp(argv[1], L"release") == 0) { exit(release(semaphore_handle)); } else { fwprintf(stderr, L"invalid action '%s'\nSupported actions are 'grab' or 'release'\n", argv[1]); } exit(1); } /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */