On Wed, Nov 12, 2008 at 09:39, Christian <christian_at_atombrenner.de> wrote:
> "A solution for how to start a background job from a subversion
> post-commit hook on windows. See issues 2619, 2560 and 2497"
>
> There are some issues (2619, 2560, 2497) regarding starting background
> jobs from post-commit hooks on windows. These issues are minor ones on
> Unix, all you have to do to is to redirect standard output and error.
>
> On Windows this workaround doesn't work. It is not possible to start
> background processes with the Windows "start" command. I will later
> explain why and how to get the desired behavior.
>
> Because when I first run into this issue it hits me completely
> unexpected. I wanted to update a fulltext index of the repository on
> every commit and doing this in the background was an absolute must.
> It took me a lot of time to figure out what was going on. All I could
> find were some crazy workarounds like using the scheduler (at) to start
> the real job a minute later or installing cygwin to get simulate a linux
> like environment. I even found a commercial product, the "Subversion
> Hook Accelerator" http://www.clearvision-cm.com/products/3945.html that
> solves this issue.
>
> Because I (Google) didn't find some good answer but instead
> found a lot of people having the same problem I like to
> share my findings here on the user mailing list.
>
> Problem Analysis (Windows):
> The subversion process waits for the post-commit hook process to finish.
> It does so by creating some pipes for redirecting stdin and stderr
> (Handles), creating a process that *inherits* those handles and waiting
> for all handles being closed. Unfortunately, a windows a child process
> inherits all handles (e.g. pipes) from its parent process if it is not
> created with some special flags (DETACHED_PROCESS) and bInheritHandles
> set to FALSE. Even more unfortunately the windows "start" command
> doesn't set this flags and therefore it is not possible to create a
> background job with "start" from a subversion hook script.
>
> So this is not a subversion issue. It is simply that "start" is the
> wrong tool to start a background job from a subversion hook.
> You need to start a "detached" windows process and this is what the
> so called "Subversion Hook Accelerator" probably does.
>
> Here comes the C++ source of a simple "RunDetached" program that can
> be used to start a real, detached background process from any
> subversion hook script. Build the RunDetached.exe and use it like this:
>
> RunDetached YourPath\YourProgram.exe YourFirstArg YourSecondArg
>
> -------------------------Snippet-------------------------------
> #include <windows.h>
> #include <stdio.h>
> #include <tchar.h>
>
> int _tmain()
> {
> LPWSTR pCmd = ::GetCommandLine();
>
> // skip the executable
> if (*pCmd++ == L'"') while (*pCmd++ != L'"');
> else while (*pCmd != NULL && *pCmd != L' ') ++pCmd;
> while (*pCmd++ == L' ');
>
> STARTUPINFO si;
> ZeroMemory( &si, sizeof(si) );
> si.cb = sizeof(si);
>
> PROCESS_INFORMATION pi;
> ZeroMemory( &pi, sizeof(pi) );
>
> // Start the child process.
> BOOL result = CreateProcess
> (
> NULL, // No module name (use command line)
> pCmd, // Command line
> NULL, // Process handle not inheritable
> NULL, // Thread handle not inheritable
> FALSE, // Set bInheritHandles to FALSE
> DETACHED_PROCESS, // Detach process
> NULL, // Use parent's environment block
> NULL, // Use parent's starting directory
> &si, // Pointer to STARTUPINFO structure
> &pi // Pointer to PROCESS_INFORMATION structure
> (returned)
> );
>
> if (result) return 0;
>
> wchar_t msg[2048];
> FormatMessage
> (
> FORMAT_MESSAGE_FROM_SYSTEM,
> NULL,
> ::GetLastError(),
> MAKELANGID(LANG_NEUTRAL, SUBLANG_SYS_DEFAULT),
> msg, sizeof(msg),
> NULL
> );
> fputws(msg, stderr);
> _flushall();
>
> return -1;
> }
You can also do this in about 5 lines of VBScript or JScript in a
Windows Script Host script. Use WScript.Shell.Run() and tell it to not
wait for the other program to complete.
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Received on 2008-11-12 15:44:18 CET