lsstimport.py

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#! env python

# 
# LSST Data Management System
# Copyright 2008, 2009, 2010 LSST Corporation.
# 
# This product includes software developed by the
# LSST Project (http://www.lsst.org/).
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the LSST License Statement and 
# the GNU General Public License along with this program.  If not, 
# see <http://www.lsstcorp.org/LegalNotices/>.
#

#
import sys
import imp
import functools
import os.path

#List of extensions to set global flags.  Mayb need to be extended
#for systems other than *nix and OSX.
SHARED_LIB_EXTENSION_LIST = ('.so', '.dylib')
LIB_EXCEPTION_LIST = ('_lsstcppimport.so',)

# Ensure that duplicate allocations--particularly those related to RTTI--are
# resolved by setting dynamical library loading flags.
RTLD_GLOBAL = -1
RTLD_NOW = -1
try:
    import dl
    if hasattr(dl, 'RTLD_GLOBAL'):  RTLD_GLOBAL = dl.RTLD_GLOBAL
    if hasattr(dl, 'RTLD_NOW'):     RTLD_NOW    = dl.RTLD_NOW
except ImportError:
    # 64bit linux does not have a dl module...
    pass
except SystemError:
    # ...if it does it should throw a SystemError
    pass

try:
    if RTLD_GLOBAL < 0:
        import lsst64defs
        RTLD_GLOBAL = lsst64defs.RTLD_GLOBAL   # usually 0x00100
    if RTLD_NOW < 0:
        import lsst64defs
        RTLD_NOW = lsst64defs.RTLD_NOW         # usually 0x00002
    DLFLAGS = RTLD_GLOBAL|RTLD_NOW
except ImportError:
    sys.stderr.write(
        "Could not import lsst64defs; please ensure the base package has been built (not just setup).\n"
    )

#Swigged python libraries that import other swigged python libraries need to import with RTLD_GLOBAL
#and RTLD_NOW set.  This causes problems with symbol collisions in third party packages (notably scipy).
#This cannot be fixed by using import hooks because python code generated by swig uses imp.load_module
#rather than import.  This makes it necessary to over ride imp.load_module.
#This was handled in ticket #3055:
#https://dev.lsstcorp.org/trac/ticket/3055

#Don't redefine if it's already been defined.
if 'orig_imp_load_module' not in locals():
    orig_imp_load_module = imp.load_module
    @functools.wraps(orig_imp_load_module)
    def imp_load_module(name, *args):
        pathParts = args[1].split(os.path.sep)
        extension = os.path.splitext(pathParts[-1])[-1]
        #Find all swigged LSST libs.  Load _lsstcppimport.so by adding it to the EXCEPTIONLIST
        #since it may not have lsst in the path (it's in $BASE_DIR/python, not $BASE_DIR/python/lsst).
        #Also, look for paths that look like python/lsst as that is how to know if you are in an LSST
        #package.
        lsstIdx = [i for i, el in enumerate(pathParts) if el == 'python']
        if pathParts[-1] in LIB_EXCEPTION_LIST or (extension in  SHARED_LIB_EXTENSION_LIST and pathParts[-1].startswith('_')\
                and 'lsst' in [pathParts[i+1] for i in lsstIdx]):
            #Get currently set flags
            originalDLFlags = sys.getdlopenflags()
            #Set flags
            sys.setdlopenflags(DLFLAGS)
            try:
                module = orig_imp_load_module(name, *args)
            finally:
                #Set original flags
                sys.setdlopenflags(originalDLFlags)
        else:
            module = orig_imp_load_module(name, *args)
        return module
    imp.load_module = imp_load_module

try:
    import lsstcppimport
except ImportError:
        sys.stderr.write(
        "Could not import lsstcppimport; please ensure the base package has been built (not just setup).\n"
    )