+"""WSGI handler for serving chained WSGI modules from physical files
+
+The WSGI handler in this module examines the SCRIPT_FILENAME variable
+of the requests it handles -- that is, the physical file corresponding
+to the request, as determined by the webserver -- determining what to
+do with the request based on the extension of that file.
+
+By default, it handles files named `.wsgi' by compiling them into
+Python modules and using them, in turn, as chained WSGI handlers, but
+handlers for other extensions can be installed as well.
+
+When handling `.wsgi' files, the compiled modules are cached and
+reused until the file is modified, in which case the previous module
+is discarded and the new file contents are loaded into a new module in
+its place. When chaining such modules, an object named `wmain' is
+first looked for and called with no arguments if found. The object it
+returns is then used as the WSGI application object for that module,
+which is reused until the module is reloaded. If `wmain' is not found,
+an object named `application' is looked for instead. If found, it is
+used directly as the WSGI application object.
+
+This module itself contains both an `application' and a `wmain'
+object. If this module is used by ashd-wsgi(1) or scgi-wsgi(1) so that
+its wmain function is called, arguments can be specified to it to
+install handlers for other file extensions. Such arguments take the
+form `.EXT=MODULE.HANDLER', where EXT is the file extension to be
+handled, and the MODULE.HANDLER string is treated by splitting it
+along its last constituent dot. The part left of the dot is the name
+of a module which is imported, and the part right of the dot is the
+name of an object in that module, which should be a callable adhering
+to the WSGI specification. When called, this module will have made
+sure that the WSGI environment contains the SCRIPT_FILENAME parameter
+and that it is properly working. For example, the argument
+`.fpy=my.module.foohandler' can be given to pass requests for `.fpy'
+files to the function `foohandler' in the module `my.module' (which
+must, of course, be importable). When writing such handler functions,
+you will probably want to use the getmod() function in this module.
+"""
+
import os, threading, types
import wsgiutil
+__all__ = ["application", "wmain", "getmod", "cachedmod"]
+
class cachedmod(object):
- def __init__(self, mod, mtime):
+ """Cache entry for modules loaded by getmod()
+
+ Instances of this class are returned by the getmod()
+ function. They contain three data attributes:
+ * mod - The loaded module
+ * lock - A threading.Lock object, which can be used for
+ manipulating this instance in a thread-safe manner
+ * mtime - The time the file was last modified
+
+ Additional data attributes can be arbitrarily added for recording
+ any meta-data about the module.
+ """
+ def __init__(self, mod = None, mtime = -1):
self.lock = threading.Lock()
self.mod = mod
self.mtime = mtime
-exts = {}
modcache = {}
cachelock = threading.Lock()
return ret
def getmod(path):
+ """Load the given file as a module, caching it appropriately
+
+ The given file is loaded and compiled into a Python module. The
+ compiled module is cached and returned upon subsequent requests
+ for the same file, unless the file has changed (as determined by
+ its mtime), in which case the cached module is discarded and the
+ new file contents are reloaded in its place.
+
+ The return value is an instance of the cachedmod class, which can
+ be used for locking purposes and for storing arbitrary meta-data
+ about the module. See its documentation for details.
+ """
sb = os.stat(path)
cachelock.acquire()
try:
if path in modcache:
entry = modcache[path]
- if sb.st_mtime <= entry.mtime:
- return entry
-
- f = open(path)
- try:
- text = f.read()
- finally:
- f.close()
- code = compile(text, path, "exec")
- mod = types.ModuleType(mangle(path))
- mod.__file__ = path
- exec code in mod.__dict__
- entry = cachedmod(mod, sb.st_mtime)
- modcache[path] = entry
- return entry
+ else:
+ entry = cachedmod()
+ modcache[path] = entry
finally:
cachelock.release()
+ entry.lock.acquire()
+ try:
+ if entry.mod is None or sb.st_mtime > entry.mtime:
+ f = open(path, "r")
+ try:
+ text = f.read()
+ finally:
+ f.close()
+ code = compile(text, path, "exec")
+ mod = types.ModuleType(mangle(path))
+ mod.__file__ = path
+ exec code in mod.__dict__
+ entry.mod = mod
+ entry.mtime = sb.st_mtime
+ return entry
+ finally:
+ entry.lock.release()
-def chain(path, env, startreq):
+class handler(object):
+ def __init__(self):
+ self.lock = threading.Lock()
+ self.handlers = {}
+ self.exts = {}
+ self.addext("wsgi", "chain")
+ self.addext("wsgi2", "chain")
+
+ def resolve(self, name):
+ self.lock.acquire()
+ try:
+ if name in self.handlers:
+ return self.handlers[name]
+ p = name.rfind('.')
+ if p < 0:
+ return globals()[name]
+ mname = name[:p]
+ hname = name[p + 1:]
+ mod = __import__(mname, fromlist = ["dummy"])
+ ret = getattr(mod, hname)
+ self.handlers[name] = ret
+ return ret
+ finally:
+ self.lock.release()
+
+ def addext(self, ext, handler):
+ self.exts[ext] = self.resolve(handler)
+
+ def handle(self, env, startreq):
+ if not "SCRIPT_FILENAME" in env:
+ return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
+ path = env["SCRIPT_FILENAME"]
+ base = os.path.basename(path)
+ p = base.rfind('.')
+ if p < 0 or not os.access(path, os.R_OK):
+ return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
+ ext = base[p + 1:]
+ if not ext in self.exts:
+ return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
+ return(self.exts[ext](env, startreq))
+
+def wmain(*argv):
+ """Main function for ashd(7)-compatible WSGI handlers
+
+ Returns the `application' function. If any arguments are given,
+ they are parsed according to the module documentation.
+ """
+ ret = handler()
+ for arg in argv:
+ if arg[0] == '.':
+ p = arg.index('=')
+ ret.addext(arg[1:p], arg[p + 1:])
+ return ret.handle
+
+def chain(env, startreq):
+ path = env["SCRIPT_FILENAME"]
mod = getmod(path)
entry = None
if mod is not None:
if entry is not None:
return entry(env, startreq)
return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Invalid WSGI handler.")
-exts["wsgi"] = chain
-
-def addext(ext, handler):
- p = handler.rindex('.')
- mname = handler[:p]
- hname = handler[p + 1:]
- mod = __import__(mname, fromlist = ["dummy"])
- exts[ext] = getattr(mod, hname)
-
-def application(env, startreq):
- if not "SCRIPT_FILENAME" in env:
- return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
- path = env["SCRIPT_FILENAME"]
- base = os.path.basename(path)
- p = base.rfind('.')
- if p < 0 or not os.access(path, os.R_OK):
- return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
- ext = base[p + 1:]
- if not ext in exts:
- return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.")
- return(exts[ext](path, env, startreq))
-def wmain(*argv):
- for arg in argv:
- if arg[0] == '.':
- p = arg.index('=')
- addext(arg[1:p], arg[p + 1:])
- return application
+application = handler().handle
Dolda2000 GitWeb / ashd.git / blobdiff