bzr push into mysql-5.1 branch (vvaintroub:2728 to 2729) Bug#33031 Bug#37226

[Vladislav Vaintroub]

 2729 Vladislav Vaintroub	2008-09-01
      Bug#37226 Explicit call of my_thread_init() on Windows for every new thread.
      Bug#33031 app linked to libmysql.lib crash if run as service in vista under 
      localsystem
        
      
      There are some problems using DllMain hook functions on Windows that 
      automatically do global and per-thread initialization for libmysqld.dll
      
      1)per-thread initialization(DLL_THREAD_ATTACH)
      MySQL internally counts number of active threads that and causes a delay in in 
      my_end() if not all threads are exited. But,there are threads that can be 
      started either by Windows internally (often in TCP/IP scenarios) or by user 
      himself - those threads are not necessarily using libmysql.dll functionality, 
      but nonetheless the contribute to the count of open threads.
      
      2)process-initialization (DLL_PROCESS_ATTACH)
      my_init() calls WSAStartup that itself loads DLLs and can lead to a deadlock in 
      Windows loader.
      
      Fix is to remove dll initialization code from libmysql.dll in general case. I
      still leave an environment variable LIBMYSQL_DLLINIT, which if set to any value 
      will cause the old behavior (DLL init hooks will be called). This env.variable 
      exists only to prevent breakage of existing Windows-only applications that 
      don't do mysql_thread_init() and work ok today. Use of LIBMYSQL_DLLINIT is 
      discouraged and it will be removed in 6.0
modified:
  libmysql/dll.c

 2728 Vladislav Vaintroub	2008-09-01 [merge]
      (no message)


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