pkgloader module to be able to coexist with 2.x

Use scheme that pygtk uses to support parallel installations:

  import pkgloader
  pkgloader.require('skytools', '3.0')

  import skytools

This will allow keeping old module installed by default and new
version is used only by request.

11 files changed, 143 insertions, 9 deletions

diff --git a/python/londiste.py b/python/londiste.py
index 6b6ae2e8..745968ea 100755
--- a/python/londiste.py
+++ b/python/londiste.py
@@ -22,7 +22,12 @@ Config template::
 
 """
 
-import sys, os, os.path, optparse, skytools
+import sys, os, os.path, optparse
+
+import pkgloader
+pkgloader.require('skytools', '3.0')
+
+import skytools
 
 # python 2.3 will try londiste.py first...
 if os.path.exists(os.path.join(sys.path[0], 'londiste.py')) \
diff --git a/python/pgqadm.py b/python/pgqadm.py
index 672f7abf..bd1ff8a6 100755
--- a/python/pgqadm.py
+++ b/python/pgqadm.py
@@ -26,6 +26,10 @@ Config template::
 """
 
 import sys
+
+import pkgloader
+pkgloader.require('skytools', '3.0')
+
 import skytools, pgq
 from pgq.cascade.admin import CascadeAdmin
 
diff --git a/python/pkgloader.py b/python/pkgloader.py
new file mode 100644
index 00000000..cf7fac87
--- /dev/null
+++ b/python/pkgloader.py
@@ -0,0 +1,89 @@
+"""Loader for Skytools modules.
+
+Primary idea is to allow several major versions to co-exists.
+Secondary idea - allow checking minimal minor version.
+
+"""
+
+import sys, os, os.path, re
+
+__all__ = ['require']
+
+_top = os.path.dirname(os.path.abspath(os.path.normpath(__file__)))
+
+_pkg_cache = None
+_import_cache = {}
+_pat = re.compile('^([a-z]+)-([0-9]+).([0-9]+)$')
+
+def _load_pkg_cache():
+    global _pkg_cache
+    if _pkg_cache is not None:
+        return _pkg_cache
+    _pkg_cache = {}
+    for dir in os.listdir(_top):
+        m = _pat.match(dir)
+        if not m:
+            continue
+        modname = m.group(1)
+        modver = (int(m.group(2)), int(m.group(3)))
+        _pkg_cache.setdefault(modname, []).append((modver, dir))
+    for vlist in _pkg_cache.itervalues():
+        vlist.sort(reverse = True)
+    return _pkg_cache
+
+def _install_path(pkg, newpath):
+    for p in sys.path:
+        pname = os.path.basename(p)
+        m = _pat.match(pname)
+        if m and m.group(1) == pkg:
+            sys.path.remove(p)
+    sys.path.insert(0, newpath)
+
+def require(pkg, reqver):
+    # parse arg
+    reqval = tuple([int(n) for n in reqver.split('.')])
+    need = reqval[:2] # cut minor ver
+
+    # check if we already have one installed
+    if pkg in _import_cache:
+        got = _import_cache[pkg]
+        if need[0] != got[0] or reqval > got:
+            raise ImportError("Request for package '%s' ver '%s', have '%s'" % (
+                              pkg, reqver, '.'.join(_skytools_required_version)))
+        return
+
+    # pick best ver from available ones
+    _pkg_cache = _load_pkg_cache()
+    if pkg not in _pkg_cache:
+        return
+
+    for pkgver, pkgdir in _pkg_cache[pkg]:
+        if pkgver[0] == need[0] and pkgver >= need:
+            # install the best on
+            _install_path(pkg, os.path.join(_top, pkgdir))
+            break
+
+    # now import whatever is available
+    inst_ver = reqval
+    try:
+        mod = __import__(pkg)
+        ver_str = mod.__version__
+        # check if it is actually useful
+        full_ver = tuple([int(x) for x in full_str.split('.')])
+        if full_ver[0] != reqval[0] or reqval > full_ver:
+            raise ImportError("Request for Skytools ver '%s', got '%s'" % (
+                            reqver, full_str))
+            raise ImportError("Request for package '%s' ver '%s', have '%s'" % (
+                              pkg, reqver, full_str))
+        inst_ver = full_ver
+    except ImportError:
+        pass
+    except AttributeError:
+        pass
+
+    # remember full version
+    _import_cache[pkg] = inst_ver
+
+    return mod
+
+
diff --git a/python/qadmin.py b/python/qadmin.py
index 1d193fcf..4ab3999d 100755
--- a/python/qadmin.py
+++ b/python/qadmin.py
@@ -52,7 +52,12 @@ General options:
     --version
 '''
 
-import sys, os, readline, skytools, getopt, re
+import sys, os, readline, getopt, re
+
+import pkgloader
+pkgloader.require('skytools', '3.0')
+
+import skytools
 
 script = None
 
diff --git a/python/setadm.py b/python/setadm.py
index 2c93d4ef..1d9520a8 100755
--- a/python/setadm.py
+++ b/python/setadm.py
@@ -3,7 +3,12 @@
 """SetAdmin launcher.
 """
 
-import sys, pgq.cascade.admin
+import sys
+
+import pkgloader
+pkgloader.require('skytools', '3.0')
+
+import pgq.cascade.admin
 
 if __name__ == '__main__':
     script = pgq.cascade.admin.CascadeAdmin('cascade_admin', 'node_db', sys.argv[1:], worker_setup = False)
diff --git a/python/walmgr.py b/python/walmgr.py
index c3e8fc86..2acf4e08 100755
--- a/python/walmgr.py
+++ b/python/walmgr.py
@@ -50,6 +50,11 @@ Additional features:
 import os, sys, skytools, re, signal, time, traceback
 import errno, glob, ConfigParser, shutil
 
+import pkgloader
+pkgloader.require('skytools', '3.0')
+
+import skytools
+
 MASTER = 1
 SLAVE = 0
 
diff --git a/scripts/queue_loader.py b/scripts/queue_loader.py
index 1b3090df..97742b82 100755
--- a/scripts/queue_loader.py
+++ b/scripts/queue_loader.py
@@ -79,10 +79,13 @@ Config template::
     create_sql =
 """
 
-import sys, time, skytools
+import sys, time
 
-from pgq.cascade.worker import CascadedWorker
+import pkgloader
+pkgloader.require('skytools', '3.0')
 
+import skytools
+from pgq.cascade.worker import CascadedWorker
 from skytools import quote_ident, quote_fqident, UsageError
 
 # todo: auto table detect
diff --git a/scripts/queue_mover.py b/scripts/queue_mover.py
index 92fe5370..f52ae7a5 100755
--- a/scripts/queue_mover.py
+++ b/scripts/queue_mover.py
@@ -19,7 +19,12 @@ Config template::
     use_skylog        = 0
 """
 
-import sys, os, pgq
+import sys, os
+
+import pkgloader
+pkgloader.require('skytools', '3.0')
+
+import pgq
 
 class QueueMover(pgq.SerialConsumer):
     __doc__ = __doc__
diff --git a/scripts/queue_splitter.py b/scripts/queue_splitter.py
index dab23982..6fed65c6 100755
--- a/scripts/queue_splitter.py
+++ b/scripts/queue_splitter.py
@@ -20,7 +20,12 @@ Config template::
     use_skylog        = 0
 """
 
-import sys, pgq
+import sys
+
+import pkgloader
+pkgloader.require('skytools', '3.0')
+
+import pgq
 
 class QueueSplitter(pgq.SerialConsumer):
     __doc__ = __doc__
diff --git a/scripts/scriptmgr.py b/scripts/scriptmgr.py
index 34bdc35d..03b3aa31 100755
--- a/scripts/scriptmgr.py
+++ b/scripts/scriptmgr.py
@@ -43,7 +43,12 @@ Config template:
     disabled = 1
 """
 
-import sys, os, skytools, signal, glob, ConfigParser, time
+import sys, os, signal, glob, ConfigParser, time
+
+import pkgloader
+pkgloader.require('skytools', '3.0')
+
+import skytools
 
 command_usage = """
 %prog [options] INI CMD [subcmd args]
diff --git a/scripts/skytools_upgrade.py b/scripts/skytools_upgrade.py
index 557dbd9c..90866611 100755
--- a/scripts/skytools_upgrade.py
+++ b/scripts/skytools_upgrade.py
@@ -2,7 +2,10 @@
 
 """Upgrade script for versioned schemas."""
 
-import sys, os, re, skytools
+import sys, os, re
+
+import pkgloader
+pkgloader.require('skytools', '3.0')
 
 ver_rx = r"(\d+)([.](\d+)([.](\d+))?)?"
 ver_rc = re.compile(ver_rx)