zeroinstall/injector/policy.py

   1 """
   2 This class brings together a L{solve.Solver} to choose a set of implmentations, a
   3 L{fetch.Fetcher} to download additional components, and the user's configuration
   4 settings.
   5 """
   6
   7 # Copyright (C) 2008, Thomas Leonard
   8 # See the README file for details, or visit http://0install.net.
   9
  10 import time
  11 import sys, os
  12 from logging import info, debug, warn
  13 import arch
  14
  15 from model import *
  16 from namespaces import *
  17 import ConfigParser
  18 from zeroinstall.support import tasks, basedir
  19 from zeroinstall.injector.iface_cache import iface_cache, PendingFeed
  20 from zeroinstall.injector.trust import trust_db
  21
  22 # If we started a check within this period, don't start another one:
  23 FAILED_CHECK_DELAY = 60 * 60    # 1 Hour
  24
  25 class Policy(object):
  26         """Chooses a set of implementations based on a policy.
  27         Typical use:
  28          1. Create a Policy object, giving it the URI of the program to be run and a handler.
  29          2. Call L{solve_with_downloads}. If more information is needed, a L{fetch.Fetcher} will be used to download it.
  30          3. When all downloads are complete, the L{solver} contains the chosen versions.
  31          4. Use L{get_uncached_implementations} to find where to get these versions and download them
  32             using L{download_uncached_implementations}.
  33
  34         @ivar target_arch: target architecture for binaries
  35         @type target_arch: L{arch.Architecture}
  36         @ivar root: URI of the root interface
  37         @ivar solver: solver used to choose a set of implementations
  38         @type solver: L{solve.Solver}
  39         @ivar watchers: callbacks to invoke after recalculating
  40         @ivar help_with_testing: default stability policy
  41         @type help_with_testing: bool
  42         @ivar network_use: one of the model.network_* values
  43         @ivar freshness: seconds allowed since last update
  44         @type freshness: int
  45         @ivar handler: handler for main-loop integration
  46         @type handler: L{handler.Handler}
  47         @ivar src: whether we are looking for source code
  48         @type src: bool
  49         @ivar stale_feeds: set of feeds which are present but haven't been checked for a long time
  50         @type stale_feeds: set
  51         """
  52         __slots__ = ['root', 'watchers',
  53                      'freshness', 'handler', '_warned_offline',
  54                      'target_arch', 'src', 'stale_feeds', 'solver', '_fetcher']
  55
  56         help_with_testing = property(lambda self: self.solver.help_with_testing,
  57                                      lambda self, value: setattr(self.solver, 'help_with_testing', value))
  58
  59         network_use = property(lambda self: self.solver.network_use,
  60                                      lambda self, value: setattr(self.solver, 'network_use', value))
  61
  62         implementation = property(lambda self: self.solver.selections)
  63
  64         ready = property(lambda self: self.solver.ready)
  65
  66         def __init__(self, root, handler = None, src = False):
  67                 """
  68                 @param root: The URI of the root interface (the program we want to run).
  69                 @param handler: A handler for main-loop integration.
  70                 @type handler: L{zeroinstall.injector.handler.Handler}
  71                 @param src: Whether we are looking for source code.
  72                 @type src: bool
  73                 """
  74                 self.watchers = []
  75                 self.freshness = 60 * 60 * 24 * 30
  76                 self.src = src                          # Root impl must be a "src" machine type
  77                 self.stale_feeds = set()
  78
  79                 from zeroinstall.injector.solver import DefaultSolver
  80                 self.solver = DefaultSolver(network_full, iface_cache, iface_cache.stores)
  81
  82                 # If we need to download something but can't because we are offline,
  83                 # warn the user. But only the first time.
  84                 self._warned_offline = False
  85                 self._fetcher = None
  86
  87                 # (allow self for backwards compat)
  88                 self.handler = handler or self
  89
  90                 debug("Supported systems: '%s'", arch.os_ranks)
  91                 debug("Supported processors: '%s'", arch.machine_ranks)
  92
  93                 path = basedir.load_first_config(config_site, config_prog, 'global')
  94                 if path:
  95                         try:
  96                                 config = ConfigParser.ConfigParser()
  97                                 config.read(path)
  98                                 self.solver.help_with_testing = config.getboolean('global',
  99                                                                 'help_with_testing')
 100                                 self.solver.network_use = config.get('global', 'network_use')
 101                                 self.freshness = int(config.get('global', 'freshness'))
 102                                 assert self.solver.network_use in network_levels
 103                         except Exception, ex:
 104                                 warn("Error loading config: %s", ex)
 105
 106                 self.set_root(root)
 107
 108                 self.target_arch = arch.get_host_architecture()
 109
 110         @property
 111         def fetcher(self):
 112                 if not self._fetcher:
 113                         import fetch
 114                         self._fetcher = fetch.Fetcher(self.handler)
 115                 return self._fetcher
 116
 117         def set_root(self, root):
 118                 """Change the root interface URI."""
 119                 assert isinstance(root, (str, unicode))
 120                 self.root = root
 121                 for w in self.watchers: w()
 122
 123         def save_config(self):
 124                 """Write global settings."""
 125                 config = ConfigParser.ConfigParser()
 126                 config.add_section('global')
 127
 128                 config.set('global', 'help_with_testing', self.help_with_testing)
 129                 config.set('global', 'network_use', self.network_use)
 130                 config.set('global', 'freshness', self.freshness)
 131
 132                 path = basedir.save_config_path(config_site, config_prog)
 133                 path = os.path.join(path, 'global')
 134                 config.write(file(path + '.new', 'w'))
 135                 os.rename(path + '.new', path)
 136
 137         def recalculate(self, fetch_stale_interfaces = True):
 138                 """@deprecated: see L{solve_with_downloads} """
 139                 self.stale_feeds = set()
 140
 141                 host_arch = self.target_arch
 142                 if self.src:
 143                         host_arch = arch.SourceArchitecture(host_arch)
 144                 self.solver.solve(self.root, host_arch)
 145
 146                 if self.network_use == network_offline:
 147                         fetch_stale_interfaces = False
 148
 149                 blockers = []
 150                 for f in self.solver.feeds_used:
 151                         if f.startswith('/'): continue
 152                         feed = iface_cache.get_feed(f)
 153                         if feed is None or feed.last_modified is None:
 154                                 self.download_and_import_feed_if_online(f)      # Will start a download
 155                         elif self.is_stale(feed):
 156                                 debug("Adding %s to stale set", f)
 157                                 self.stale_feeds.add(iface_cache.get_interface(f))      # Legacy API
 158                                 if fetch_stale_interfaces:
 159                                         self.download_and_import_feed_if_online(f)      # Will start a download
 160
 161                 for w in self.watchers: w()
 162
 163                 return blockers
 164
 165         def usable_feeds(self, iface):
 166                 """Generator for C{iface.feeds} that are valid for our architecture.
 167                 @rtype: generator
 168                 @see: L{arch}"""
 169                 if self.src and iface.uri == self.root:
 170                         # Note: when feeds are recursive, we'll need a better test for root here
 171                         machine_ranks = {'src': 1}
 172                 else:
 173                         machine_ranks = arch.machine_ranks
 174
 175                 for f in iface.feeds:
 176                         if f.os in arch.os_ranks and f.machine in machine_ranks:
 177                                 yield f
 178                         else:
 179                                 debug("Skipping '%s'; unsupported architecture %s-%s",
 180                                         f, f.os, f.machine)
 181
 182         def is_stale(self, feed):
 183                 """Check whether feed needs updating, based on the configured L{freshness}.
 184                 None is considered to be stale.
 185                 @return: true if feed is stale or missing."""
 186                 if feed is None:
 187                         return True
 188                 if feed.url.startswith('/'):
 189                         return False            # Local feeds are never stale
 190                 if feed.last_modified is None:
 191                         return True             # Don't even have it yet
 192                 now = time.time()
 193                 staleness = now - (feed.last_checked or 0)
 194                 debug("Staleness for %s is %.2f hours", feed, staleness / 3600.0)
 195
 196                 if self.freshness == 0 or staleness < self.freshness:
 197                         return False            # Fresh enough for us
 198
 199                 last_check_attempt = iface_cache.get_last_check_attempt(feed.url)
 200                 if last_check_attempt and last_check_attempt > now - FAILED_CHECK_DELAY:
 201                         debug("Stale, but tried to check recently (%s) so not rechecking now.", time.ctime(last_check_attempt))
 202                         return False
 203
 204                 return True
 205
 206         def download_and_import_feed_if_online(self, feed_url):
 207                 """If we're online, call L{fetch.Fetcher.download_and_import_feed}. Otherwise, log a suitable warning."""
 208                 if self.network_use != network_offline:
 209                         debug("Feed %s not cached and not off-line. Downloading...", feed_url)
 210                         return self.fetcher.download_and_import_feed(feed_url, iface_cache)
 211                 else:
 212                         if self._warned_offline:
 213                                 debug("Not downloading feed '%s' because we are off-line.", feed_url)
 214                         elif feed_url == injector_gui_uri:
 215                                 # Don't print a warning, because we always switch to off-line mode to
 216                                 # run the GUI the first time.
 217                                 info("Not downloading GUI feed '%s' because we are in off-line mode.", feed_url)
 218                         else:
 219                                 warn("Not downloading feed '%s' because we are in off-line mode.", feed_url)
 220                                 self._warned_offline = True
 221
 222         def get_implementation_path(self, impl):
 223                 """Return the local path of impl.
 224                 @rtype: str
 225                 @raise zeroinstall.zerostore.NotStored: if it needs to be added to the cache first."""
 226                 assert isinstance(impl, Implementation)
 227                 if impl.id.startswith('/'):
 228                         return impl.id
 229                 return iface_cache.stores.lookup(impl.id)
 230
 231         def get_implementation(self, interface):
 232                 """Get the chosen implementation.
 233                 @type interface: Interface
 234                 @rtype: L{model.Implementation}
 235                 @raise SafeException: if interface has not been fetched or no implementation could be
 236                 chosen."""
 237                 assert isinstance(interface, Interface)
 238
 239                 if not interface.name and not interface.feeds:
 240                         raise SafeException("We don't have enough information to "
 241                                             "run this program yet. "
 242                                             "Need to download:\n%s" % interface.uri)
 243                 try:
 244                         return self.implementation[interface]
 245                 except KeyError, ex:
 246                         if interface.implementations:
 247                                 offline = ""
 248                                 if self.network_use == network_offline:
 249                                         offline = "\nThis may be because 'Network Use' is set to Off-line."
 250                                 raise SafeException("No usable implementation found for '%s'.%s" %
 251                                                 (interface.name, offline))
 252                         raise ex
 253
 254         def get_cached(self, impl):
 255                 """Check whether an implementation is available locally.
 256                 @type impl: model.Implementation
 257                 @rtype: bool
 258                 """
 259                 if isinstance(impl, DistributionImplementation):
 260                         return impl.installed
 261                 if impl.id.startswith('/'):
 262                         return os.path.exists(impl.id)
 263                 else:
 264                         try:
 265                                 path = self.get_implementation_path(impl)
 266                                 assert path
 267                                 return True
 268                         except:
 269                                 pass # OK
 270                 return False
 271
 272         def get_uncached_implementations(self):
 273                 """List all chosen implementations which aren't yet available locally.
 274                 @rtype: [(str, model.Implementation)]"""
 275                 uncached = []
 276                 for iface in self.solver.selections:
 277                         impl = self.solver.selections[iface]
 278                         assert impl, self.solver.selections
 279                         if not self.get_cached(impl):
 280                                 uncached.append((iface, impl))
 281                 return uncached
 282
 283         def refresh_all(self, force = True):
 284                 """Start downloading all feeds for all selected interfaces.
 285                 @param force: Whether to restart existing downloads."""
 286                 return self.solve_with_downloads(force = True)
 287
 288         def get_feed_targets(self, feed_iface_uri):
 289                 """Return a list of Interfaces for which feed_iface can be a feed.
 290                 This is used by B{0launch --feed}.
 291                 @rtype: [model.Interface]
 292                 @raise SafeException: If there are no known feeds."""
 293                 # TODO: what if it isn't cached yet?
 294                 feed_iface = iface_cache.get_interface(feed_iface_uri)
 295                 if not feed_iface.feed_for:
 296                         if not feed_iface.name:
 297                                 raise SafeException("Can't get feed targets for '%s'; failed to load interface." %
 298                                                 feed_iface_uri)
 299                         raise SafeException("Missing <feed-for> element in '%s'; "
 300                                         "this interface can't be used as a feed." % feed_iface_uri)
 301                 feed_targets = feed_iface.feed_for
 302                 debug("Feed targets: %s", feed_targets)
 303                 if not feed_iface.name:
 304                         warn("Warning: unknown interface '%s'" % feed_iface_uri)
 305                 return [iface_cache.get_interface(uri) for uri in feed_targets]
 306
 307         @tasks.async
 308         def solve_with_downloads(self, force = False):
 309                 """Run the solver, then download any feeds that are missing or
 310                 that need to be updated. Each time a new feed is imported into
 311                 the cache, the solver is run again, possibly adding new downloads.
 312                 @param force: whether to download even if we're already ready to run."""
 313
 314                 downloads_finished = set()              # Successful or otherwise
 315                 downloads_in_progress = {}              # URL -> Download
 316
 317                 host_arch = self.target_arch
 318                 if self.src:
 319                         host_arch = arch.SourceArchitecture(host_arch)
 320
 321                 while True:
 322                         self.solver.solve(self.root, host_arch)
 323                         for w in self.watchers: w()
 324
 325                         if self.solver.ready and not force:
 326                                 break
 327                         else:
 328                                 # Once we've starting downloading some things,
 329                                 # we might as well get them all.
 330                                 force = True
 331
 332                         if not self.network_use == network_offline:
 333                                 for f in self.solver.feeds_used:
 334                                         if f in downloads_finished or f in downloads_in_progress:
 335                                                 continue
 336                                         if f.startswith('/'):
 337                                                 continue
 338                                         feed = iface_cache.get_interface(f)
 339                                         downloads_in_progress[f] = self.fetcher.download_and_import_feed(f, iface_cache)
 340
 341                         if not downloads_in_progress:
 342                                 break
 343
 344                         blockers = downloads_in_progress.values()
 345                         yield blockers
 346                         tasks.check(blockers, self.handler.report_error)
 347
 348                         for f in downloads_in_progress.keys():
 349                                 if downloads_in_progress[f].happened:
 350                                         del downloads_in_progress[f]
 351                                         downloads_finished.add(f)
 352
 353         def need_download(self):
 354                 """Decide whether we need to download anything (but don't do it!)
 355                 @return: true if we MUST download something (feeds or implementations)
 356                 @rtype: bool"""
 357                 host_arch = self.target_arch
 358                 if self.src:
 359                         host_arch = arch.SourceArchitecture(host_arch)
 360                 self.solver.solve(self.root, host_arch)
 361                 for w in self.watchers: w()
 362
 363                 if not self.solver.ready:
 364                         return True             # Maybe a newer version will work?
 365
 366                 if self.get_uncached_implementations():
 367                         return True
 368
 369                 return False
 370
 371         def download_uncached_implementations(self):
 372                 """Download all implementations chosen by the solver that are missing from the cache."""
 373                 assert self.solver.ready, "Solver is not ready!\n%s" % self.solver.selections
 374                 return self.fetcher.download_impls([impl for impl in self.solver.selections.values() if not self.get_cached(impl)],
 375                                                    iface_cache.stores)
 376
 377         def download_icon(self, interface, force = False):
 378                 """Download an icon for this interface and add it to the
 379                 icon cache. If the interface has no icon or we are offline, do nothing.
 380                 @return: the task doing the import, or None
 381                 @rtype: L{tasks.Task}"""
 382                 debug("download_icon %s (force = %d)", interface, force)
 383
 384                 if self.network_use == network_offline:
 385                         info("No icon present for %s, but off-line so not downloading", interface)
 386                         return
 387
 388                 return self.fetcher.download_icon(interface, force)
 389
 390         def get_interface(self, uri):
 391                 """@deprecated: use L{iface_cache.IfaceCache.get_interface} instead"""
 392                 import warnings
 393                 warnings.warn("Policy.get_interface is deprecated!", DeprecationWarning, stacklevel = 2)
 394                 return iface_cache.get_interface(uri)