X-Git-Url: http://www.dolda2000.com/gitweb/?p=ashd.git;a=blobdiff_plain;f=python%2Fashd%2Fwsgidir.py;h=6bf00b65f58f0656c966c21d03910d2309670af1;hp=212c4b73ef4ca20a2bd1e486e42ac2b5851da4d7;hb=58ee5c4ab4ce9be692277b520de72735494bd9f7;hpb=36ea06a63bb12fed3406b3e7bbbcd87633877045 diff --git a/python/ashd/wsgidir.py b/python/ashd/wsgidir.py index 212c4b7..6bf00b6 100644 --- a/python/ashd/wsgidir.py +++ b/python/ashd/wsgidir.py @@ -1,7 +1,63 @@ -import os, threading, types +"""WSGI handler for serving chained WSGI modules from physical files + +The WSGI handler in this module ensures that the SCRIPT_FILENAME +variable is properly set in every request and points out a file that +exists and is readable. It then dispatches the request in one of two +ways: If the header X-Ash-Python-Handler is set in the request, its +value is used as the name of a handler object to dispatch the request +to; otherwise, the file extension of the SCRIPT_FILENAME is used to +determine the handler object. + +The name of a handler object is specified as a string, which is split +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. Alternatively, the module part may be +omitted (such that the name is a string with no dots), in which case +the handler object is looked up from this module. + +By default, this module will handle files with the extensions `.wsgi' +or `.wsgi2' using the `chain' handler, which chainloads such files and +runs them as independent WSGI applications. See its documentation for +details. + +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=HANDLER', where EXT is the file extension to be handled, +and HANDLER is a handler name, as described above. 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 may want to use the getmod() function in this module. +""" + +import sys, os, threading, types, logging, getopt import wsgiutil -exts = {} +__all__ = ["application", "wmain", "getmod", "cachedmod", "chain"] + +log = logging.getLogger("wsgidir") + +class cachedmod(object): + """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 + modcache = {} cachelock = threading.Lock() @@ -15,48 +71,150 @@ def mangle(path): 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: - mod, mtime = modcache[path] - if sb.st_mtime <= mtime: - return mod - 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__ - modcache[path] = mod, sb.st_mtime - return mod + entry = modcache[path] + else: + entry = [threading.Lock(), None] + modcache[path] = entry finally: cachelock.release() + entry[0].acquire() + try: + if entry[1] is None or sb.st_mtime > entry[1].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[1] = cachedmod(mod, sb.st_mtime) + return entry[1] + finally: + entry[0].release() -def chain(path, env, startreq): - mod = getmod(path) - if hasattr(mod, "wmain"): - return (mod.wmain())(env, startreq) - elif hasattr(mod, "application"): - return mod.application(env, startreq) - return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Invalid WSGI handler.") -exts["wsgi"] = chain +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"] + if not os.access(path, os.R_OK): + return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.") + if "HTTP_X_ASH_PYTHON_HANDLER" in env: + handler = self.resolve(env["HTTP_X_ASH_PYTHON_HANDLER"]) + else: + base = os.path.basename(path) + p = base.rfind('.') + if p < 0: + 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.") + handler = self.exts[ext] + return handler(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. + """ + hnd = handler() + ret = hnd.handle -def application(env, startreq): - if not "SCRIPT_FILENAME" in env: - return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "The server is erroneously configured.") + opts, args = getopt.getopt(argv, "V") + for o, a in opts: + if o == "-V": + import wsgiref.validate + ret = wsgiref.validate.validator(ret) + + for arg in args: + if arg[0] == '.': + p = arg.index('=') + hnd.addext(arg[1:p], arg[p + 1:]) + return ret + +def chain(env, startreq): + """Chain-loading WSGI handler + + This handler loads requested files, compiles them and loads them + into their own modules. 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. + """ 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): - return application + try: + mod = getmod(path) + except Exception: + log.error("Exception occurred when loading %s" % path, exc_info=sys.exc_info()) + return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Could not load WSGI handler.") + entry = None + if mod is not None: + mod.lock.acquire() + try: + if hasattr(mod, "entry"): + entry = mod.entry + else: + if hasattr(mod.mod, "wmain"): + entry = mod.mod.wmain() + elif hasattr(mod.mod, "application"): + entry = mod.mod.application + mod.entry = entry + finally: + mod.lock.release() + if entry is not None: + return entry(env, startreq) + return wsgiutil.simpleerror(env, startreq, 500, "Internal Error", "Invalid WSGI handler.") + +application = handler().handle