69 строки
3.0 KiB
Plaintext
69 строки
3.0 KiB
Plaintext
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Last updated: 15 Sep 2010
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How to update the Libevent embedded in OPAL
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OPAL requires some modification of the Libevent build system in order
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to properly operate. In addition, OPAL accesses the Libevent functions
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through a set of wrappers - this is done for three reasons:
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1. Hide the Libevent functions. Some applications directly call
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libevent APIs and expect to operate against a locally installed
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library. Since the library used by OPAL may differ in version, and
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to avoid linker errors for multiply-defined symbols, it is
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important that the libevent functions included in OPAL be "hidden"
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from external view. Thus, OPAL's internal copy of libevent is built
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with visibility set to "hidden" and all access from the OPAL code
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base is done through "opal_xxx" wrapper API calls.
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In those cases where the system is built against a compiler that
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doesn't support visibility, conflicts can (unfortunately)
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arise. However, since only a very few applications would be
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affected, and since most compilers support visibility, we do not
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worry about this possibility.
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2. Correct some deficiencies in the distributed Libevent configuration
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tests. Specifically, the distributed tests for kqueue and epoll
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support provide erroneous results on some platforms (as determined
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by our empirical testing). OPAL therefore provides enhanced tests
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to correctly assess those environments.
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3. Enable greater flexibility in configuring Libevent for the specific
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environment. In particular, OPAL has no need of Libevent's dns,
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http, and rpc events, so configuration options to remove that code
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from Libevent have been added.
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The procedure for updating Libevent has been greatly simplified
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compared to prior versions in the OPAL code base by replacing
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file-by-file edits with configuration logic. Thus, updating the
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included libevent code can generally be accomplished by:
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1. svn delete the contents of the opal/event/libevent directory
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--> We may want to do this via SVN 3rd party update. Not clear yet.
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2. unpack the new libevent code tarball in the opal/event/libevent directory
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--> We may want to do this via SVN 3rd party update. Not clear yet.
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3. restore the symbolic link:
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cd libevent/m4
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ln -s ../../opal_libevent_configure.m4 opal_libevent_configure.m4
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4. edit libevent/configure.in to add two lines:
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(a) just before AC_PROG_LIBTOOL near the beginning of the file:
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OPAL_CONFIGURE_LIBEVENT_OPTIONS
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(b) just before AC_CONFIG_FILES at the very end:
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OPAL_CONFIGURE_LIBEVENT_MODES
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5. Merge the contents of opal_libevent_makefile.am with
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libevent/Makefile.am. Depending upon what the Libevent developers
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did for the update, this may well need to be done by hand.
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6. Edit libevent/configure.in and add the following after the
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AM_INIT_AUTOMAKE line:
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# If Automake supports silent rules, enable them.
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m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
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This isn't critical, but it makes the compiler output MUCH
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prettier (and consistent with OMPI).
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