#!/usr/bin/python

#

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# Copyright 2007 Sun Microsystems, Inc.  All rights reserved.

# Use is subject to license terms.

#

import os

import re

import time

import datetime

import pkg.fmri as fmri

import pkg.catalog as catalog

class UpdateLogException(Exception):

        def __init__(self, args=None):

                self.args = args

class UpdateLog(object):

        """The update log is a mechanism that allows clients and servers to make

        incremental updates to their package catalogs.  The server logs

        whether it has added or removed a package, the time when the action

        occurred, and the name of the package added or removed.  The client

        requests a list of actions that have been applied to the server's

        catalog since a particular time in the past.  The server is then able to

        send this list of actions, allowing the client to apply these changes to

        its catalog.

        This allows the client to obtain incremental updates to its catalog,

        instead of having to download an entire (and largely duplicated)

        catalog each time a refresh is requested.

        The UpdateLog must have an associated catalog; however,

        Catalogs are not required to have an UpdateLog.  The UpdateLog

        allows catalogs to support incremental updates.

        The catalog format is a + or -, an isoformat timestamp, and a catalog

        entry in server-side format.  They must be in order and separated by

        spaces."""

        def __init__(self, update_root, catalog, maxfiles = 336):

                """Create an instance of the UpdateLog.  "update_root" is

                the root directory for the update log files.

                maxfiles is the maximum number of logfiles that

                the UpdateLog will keep.  A new file is added

                for each hour in which there is an update.  The

                default value of 336 means that we keep 336 hours, or

                14 days worth of log history."""

                self.rootdir = update_root

                self.logfd = None

                self.maxfiles = maxfiles

                self.catalog = catalog

                if not os.path.exists(update_root):

                        os.makedirs(update_root)

                self._setup_logfiles()

        def __del__(self):

                """Perform any last minute cleanup."""

                if self.logfd:

                        try:

                                self.logfd.close()

                        except:

                                pass

                        self.logfd = None

        def add_package(self, fmri, critical = False):

                """Record that the catalog has added "fmri"."""

                # First add FMRI to catalog

                ts = self.catalog.add_fmri(fmri, critical)

                # Now add update to updatelog

                self._check_logs()

                if not self.logfd:

                        self._begin_log()

                if critical:

                        type = "C"

                else:

                        type = "V"

                logstr = "+ %s %s %s\n" % \

                    (ts.isoformat(), type, fmri.get_fmri(anarchy = True))

                self.logfd.write(logstr)

                self.logfd.flush()

                self.last_update = ts

                return ts

        def _begin_log(self):

                """Open a log-file so that the UpdateLog can write updates

                into it."""

                filenm = time.strftime("%Y%m%d%H")

                ftime = datetime.datetime(

                    *time.strptime(filenm, "%Y%m%d%H")[0:6])

                delta = datetime.timedelta(hours=1)

                self.close_time = ftime + delta

                self.logfd = file(os.path.join(self.rootdir, filenm), "a")

                if not self.first_update:

                        self.first_update = ftime

        def _check_logs(self):

                """Check to see if maximum number of logfiles has been exceeded.

                If so, rotate the logs.  Also, if a log is open, check to

                see if it needs to be closed."""

                if self.logfd and self.close_time < datetime.datetime.now():

                        self.logfd.close()

                        self.logfd = None

                        self.close_time = 0

                if self.curfiles < self.maxfiles:

                        return

                excess = self.curfiles - self.maxfiles

                to_remove = self.logfiles[0:excess]

                for r in to_remove:

                        filepath = os.path.join(self.rootdir, "%s" % r)

                        os.unlink(filepath)

                        self.curfiles -= 1 

                del self.logfiles[0:excess]

                self.first_update = datetime.datetime(*time.strptime(

                    self.logfiles[0], "%Y%m%d%H")[0:6])

        def enough_history(self, ts):

                """Returns true if the timestamp is so far behind the

                update log, that there is not enough log history to bring

                the client up to date."""

                # Absence of server-side log history also counts as

                # not enough history.

                if not self.last_update or not self.first_update:

                        return False

                if ts < self.first_update:

                        return False

                return True

        @staticmethod

        def recv(c, path, ts):

                """Take a connection object and a catalog path.  This method

                receives a catalog from the server.  If it is an incremental

                update, it is processed by the updatelog.  If it is a full

                update, we call the catalog to handle the request.

                Ts is the timestamp when the local copy of the catalog

                was last modified."""

                update_type = c.info().getheader("X-Catalog-Type", "full")

                if update_type == 'incremental':

                        UpdateLog._recv_updates(c, path, ts)

                else:

                        catalog.recv(c, path)

        @staticmethod

        def _recv_updates(filep, path, cts):

                """A static method that takes a file-like object,

                a path, and a timestamp.  This is the other half of

                send_updates().  It reads a stream as an incoming updatelog and

                modifies the catalog on disk."""

                if not os.path.exists(path):

                        os.makedirs(path)

                # Build a list of FMRIs that this update would add, check to

                # make sure that they aren't present in the catalog, then append

                # the fmris.

                mts = catalog.ts_to_datetime(cts)

                cts = mts

                added = 0

                npkgs = 0

                add_lines = []

                unknown_lines = []

                attrs = {}

                for s in filep:

                        if len(l) < 4:

                                continue

                        elif l[2] not in catalog.known_prefixes:

                                # Add unknown line directly to catalog.

                                # This can be post-processed later, when it

                                # becomes known.

                                #

                                # XXX Notify user that unknown entry was added?

                                ts = catalog.ts_to_datetime(l[1])

                                if ts > cts:

                                        if ts > mts:

                                                mts = ts

                                        str = "%s %s\n" % (l[2], l[3])

                                        unknown_lines.append(str)

                        elif l[0] == "+":

                                # This is a known entry type.

                                # Create a list of FMRIs to add, since

                                # additional inspection is required

                                ts = catalog.ts_to_datetime(l[1])

                                if ts > cts:

                                        if ts > mts:

                                                mts = ts

                # Verify that they aren't already in the catalog

                catf = file(os.path.normpath(

                    os.path.join(path, "catalog")), "a+")

                catf.seek(0)

                for c in catf:

                        if c in add_lines:

                                catf.close()

                                raise UpdateLogException, \

                                    "Package %s is already in the catalog" % \

                                        c

                # Write the new entries to the catalog

                catf.seek(0, 2)

                catf.writelines(add_lines)

                if len(unknown_lines) > 0:

                        catf.writelines(unknown_lines)

                catf.close()

                # Now re-write npkgs and Last-Modified in attributes file

                afile = file(os.path.normpath(os.path.join(path, "attrs")), "r")

                attrre = re.compile('^S ([^:]*): (.*)')

                for entry in afile:

                        m = attrre.match(entry)

                        if m != None:

                                attrs[m.group(1)] = m.group(2)

                afile.close()

                # Update the attributes we care about

                attrs["npkgs"] = npkgs + added

                attrs["Last-Modified"] = mts.isoformat()

                # Write attributes back out

                afile = file(os.path.normpath(os.path.join(path, "attrs")), "w")

                for a in attrs.keys():

                        s = "S %s: %s\n" % (a, attrs[a])

                        afile.write(s)

                afile.close()

                return True

        def send(self, request):

                """This method takes a http request and sends a catalog

                to the client.  If the client it capable of receiving an

                incremental update, we'll send that.  Otherwise, it calls

                into the catalog to send a full copy."""

                modified = request.headers.getheader("If-Modified-Since")

                ts = None

                if modified:

                        try:

                                ts = catalog.ts_to_datetime(modified)

                        except ValueError:

                                ts = None

                # Incremental catalog updates

                if ts and self.up_to_date(ts):

                        request.send_response(304)

                        request.send_header('Content-type', 'text/plain')

                        request.send_header('Last-Modified',

                            self.catalog.last_modified())

                        request.send_header('X-Catalog-Type', 'incremental')

                        request.end_headers()

                        return

                elif ts and self.enough_history(ts):

                        request.send_response(200)

                        request.send_header('Content-type', 'text/plain')

                        request.send_header('Last-Modified',

                            self.catalog.last_modified())

                        request.send_header('X-Catalog-Type', 'incremental')

                        request.end_headers()

                        self._send_updates(ts, request.wfile)

                        return

                else:

                        # Not enough history, or full catalog requested

                        request.send_response(200)

                        request.send_header('Content-type', 'text/plain')

                        request.send_header('X-Catalog-Type', 'full')

                        request.end_headers()

                        self.catalog.send(request.wfile)

                        return

        def _send_updates(self, ts, filep):

                """Look through the logs for updates that have occurred

                after timestamp.  Write these changes to the file-like object

                supplied in filep."""

                # The files that need to be examined depend upon the timestamp

                # supplied by the client, and the log files actually present.

                #

                # The following cases exist:

                #

                # 1. No updates have occurred since timestamp.  Send nothing.

                #

                # 2. Timestamp is older than oldest log record.  Client needs to

                # download full catalog.

                #

                # 3. Timestamp falls within a range for which update records

                # exist.  If the timestamp is in the middle of a log-file, open

                # that file, send updates newer than timestamp, and then send

                # all newer files.  Otherwise, just send updates from the newer

                # log files.

                if self.up_to_date(ts) or not self.enough_history(ts):

                       return

                # Remove minutes, seconds, and microsec from timestamp

                rts = datetime.datetime(ts.year, ts.month, ts.day, ts.hour)

                assert rts < ts

                # send data from logfiles newer or equal to rts

                for lf in self.logfiles:

                        lf_time = datetime.datetime(

                            *time.strptime(lf, "%Y%m%d%H")[0:6])

                        if lf_time >= rts:

                                fn = "%s" % lf

                                logf = file(os.path.join(self.rootdir, fn), "r")

                                for line in logf:

                                        filep.write(line)

                                logf.close()

        def _setup_logfiles(self):

                """Scans the directory containing the update log's files.

                Sets up any necessary state for the UpdateLog."""

                # Store names of logfiles as integers for easier comparison

                self.logfiles = [f for f in os.listdir(self.rootdir)]

                self.logfiles.sort()

                self.curfiles = len(self.logfiles)

                if self.curfiles == 0:

                        self.last_update = None

                        self.first_update = None

                        return

                # Find the last update by opening the most recent logfile

                # and finding its last entry

                filenm = self.logfiles[self.curfiles - 1]

                logf = file(os.path.join(self.rootdir, filenm), "r")

                last_update = None

                for ln in logf:

                        lspl = ln.split(" ", 4)

                        if len(lspl) < 4:

                                continue

                        current_ts = catalog.ts_to_datetime(lspl[1])

                        if not last_update or current_ts > last_update:

                                last_update = current_ts

                logf.close()

                self.last_update = last_update

                self.first_update = datetime.datetime(

                    *time.strptime(self.logfiles[0], "%Y%m%d%H")[0:6])

        def up_to_date(self, ts):

                """Returns true if the timestamp is up to date."""

                if self.last_update and ts >= self.last_update:

                        return True

                return False

# Allow these methods to be invoked without explictly naming the UpdateLog

# class.

recv = UpdateLog.recv