Introduce method collect_libraries_to_load

This will allow us to remove the hardcoded entries from the different java files of the bootstraps so we will use this method to load the corresponding libraries depending on the bootstrap and the recipes which we use in our builds.

Author: opacam

pythonforandroid/bootstrap.py

@@ -8,8 +8,8 @@
 
 from pythonforandroid.logger import (warning, shprint, info, logger,
                                      debug)
-from pythonforandroid.util import (current_directory, ensure_dir,
-                                   temp_directory, which)
+from pythonforandroid.util import (current_directory, ensure_dir, which,
+                                   temp_directory, BuildInterruptingException)
 from pythonforandroid.recipe import Recipe
 
 
@@ -36,6 +36,10 @@ def copy_files(src_root, dest_root, override=True):
 class Bootstrap(object):
     '''An Android project template, containing recipe stuff for
     compilation and templated fields for APK info.
+
+    .. versionchanged:: 0.6.0
+        Adds attribute :attr:`libraries_to_load` and method
+        :meth:`collect_libraries_to_load`.
     '''
     name = ''
     jni_subdir = '/jni'
@@ -56,6 +60,11 @@ class Bootstrap(object):
     from Bootstrap.get_bootstrap_from_recipes.
     '''
 
+    libraries_to_load = []
+    '''The list of libraries that should be loaded by android on python's app
+    initialization. This list will be dynamically created at
+    :meth:`collect_libraries_to_load` depending on the recipes build order.'''
+
     # Other things a Bootstrap might need to track (maybe separately):
     # ndk_main.c
     # whitelist.txt
@@ -257,6 +266,83 @@ def _unpack_aar(self, aar, arch):
             for f in so_files:
                 shprint(sh.cp, '-a', f, so_tgt_dir)
 
+    def collect_libraries_to_load(self, arch):
+        '''
+        Collect the shared libraries needed to load when apk initialises and
+        returns a list. This list will be used to create a file in our
+        distribution's assets folder which will be used by our java loading
+        mechanism to load those shared libraries at runtime.
+
+        .. warning:: the loading order matters, this cannot be arbitrary,
+            for example, if some lib has been build against our python, then
+            needs to be loaded after the python library has been loaded.
+        '''
+        info('Collect compiled shared libraries to load at runtime')
+
+        libs_to_load = []
+        # Add libs that should be loaded before bootstrap libs (here goes some
+        # special shared libs, like stl libs used at compile time or libs that
+        # the bootstrap may be dependant).
+        # Todo: All the recipes using gnustl_shared should be migrated to use
+        # c++_shared because in ndk r18 it will be the only stl available:
+        # https://developer.android.com/ndk/guides/cpp-support
+        for recipe_name in self.ctx.recipe_build_order:
+            recipe = Recipe.get_recipe(recipe_name, self.ctx)
+            if recipe.stl_depends is None:
+                continue
+            if recipe.stl_depends not in ('c++_shared', 'gnustl_shared'):
+                raise BuildInterruptingException(
+                    'You have a non supported value in attribute stl_depends '
+                    '"{stl_lib}" for recipe "{recipe_name}". The'
+                    'value should be one of: "c++_shared" or "gnustl_shared"'.format(
+                        stl_lib=recipe.stl_depends, recipe_name=recipe.name))
+            if recipe.stl_depends not in libs_to_load:
+                libs_to_load.append(recipe.stl_depends)
+            if all(lib in libs_to_load for lib in ('c++_shared', 'gnustl_shared')):
+                break
+
+        # Add crystax if necessary
+        if self.ctx.python_recipe.from_crystax:
+            libs_to_load.append('crystax')
+
+        # Add libraries that python depends on
+        if 'sqlite3' in self.ctx.recipe_build_order:
+            libs_to_load.append('sqlite3')
+        if 'libffi' in self.ctx.recipe_build_order:
+            libs_to_load.append('ffi')
+        if 'openssl' in self.ctx.recipe_build_order:
+            recipe = Recipe.get_recipe('openssl', self.ctx)
+            libs_to_load.append('ssl' + recipe.version)
+            libs_to_load.append('crypto' + recipe.version)
+
+        # Add the bootstrap libs
+        [libs_to_load.append(i) for i in self.libraries_to_load]
+
+        # Add the corresponding python lib
+        python_version = self.ctx.python_recipe.major_minor_version_string
+        if python_version[0] == '3':
+            python_version += 'm'
+        libs_to_load.append('python' + python_version)
+
+        # Add libs that should be loaded after python because depends on it
+        if 'boost' in self.ctx.recipe_build_order:
+            # Todo: check boost loading dependencies and create a proper
+            # loading order. For now it works for libtorrent's recipe, the only
+            # recipe that depends on boost...so...for now it's fine, but should
+            # be enhanced, maybe using similar method than
+            # `pythonforandroid.build.copylibs_function`?
+            for l in listdir(self.ctx.get_libs_dir(arch.arch)):
+                if l.startswith('libboost_'):
+                    libs_to_load.append(l[3:-3])
+        if 'libtorrent' in self.ctx.recipe_build_order:
+            libs_to_load.append('torrent_rasterbar')
+        if 'libiconv' in self.ctx.recipe_build_order:
+            libs_to_load.append('iconv')
+        if 'libzbar' in self.ctx.recipe_build_order:
+            libs_to_load.append('zbar')
+
+        return libs_to_load
+
     def strip_libraries(self, arch):
         info('Stripping libraries')
         if self.ctx.python_recipe.from_crystax: