Add a function to choose content signature type. (Anthony Roach)

5 files changed, 43 insertions, 19 deletions

diff --git a/src/CHANGES.txt b/src/CHANGES.txt
index 0b1b027..c91a59e 100644
--- a/src/CHANGES.txt
+++ b/src/CHANGES.txt
@@ -96,6 +96,9 @@ RELEASE 0.09 -
 
   - Fix the overly-verbose stack trace on ListBuilder build errors.
 
+  - Add a SetContentSignatureType() function, allowing use of file
+    timestamps instead of MD5 signatures.
+
   From sam th:
 
   - Dynamically check for the existence of utilities with which to
diff --git a/src/engine/SCons/Script/SConscript.py b/src/engine/SCons/Script/SConscript.py
index cb20ae9..2802e8f 100644
--- a/src/engine/SCons/Script/SConscript.py
+++ b/src/engine/SCons/Script/SConscript.py
@@ -39,7 +39,6 @@ import SCons.Node.FS
 import SCons.Platform
 import SCons.Tool
 import SCons.Util
-import SCons.Sig
 import SCons.Options
 import SCons
 
@@ -258,6 +257,7 @@ def GetLaunchDir():
     return launch_dir
 
 def SetBuildSignatureType(type):
+    import SCons.Sig
     if type == 'build':
         SCons.Sig.build_signature = 1
     elif type == 'content':
@@ -265,6 +265,18 @@ def SetBuildSignatureType(type):
     else:
         raise SCons.Errors.UserError, "Unknown build signature type '%s'"%type
 
+def SetContentSignatureType(type):
+    import SCons.Script
+    if type == 'MD5':
+        import SCons.Sig.MD5
+        SCons.Script.sig_module = SCons.Sig.MD5
+    elif type == 'timestamp':
+        import SCons.Sig.TimeStamp
+        SCons.Script.sig_module = SCons.Sig.TimeStamp
+    else:
+        raise SCons.Errors.UserError, "Unknown content signature type '%s'"%type
+
+
 class Options(SCons.Options.Options):
     def Update(self, env):
         return SCons.Options.Options.Update(self, env, arguments)
@@ -321,6 +333,7 @@ def BuildDefaultGlobals():
     globals['Object']            = SCons.Defaults.StaticObject
     globals['Repository']        = SCons.Node.FS.default_fs.Repository
     globals['SetBuildSignatureType'] = SetBuildSignatureType
+    globals['SetContentSignatureType'] = SetContentSignatureType
     globals['StaticLibrary']     = SCons.Defaults.StaticLibrary
     globals['StaticObject']      = SCons.Defaults.StaticObject
     globals['SharedLibrary']     = SCons.Defaults.SharedLibrary
diff --git a/src/engine/SCons/Script/__init__.py b/src/engine/SCons/Script/__init__.py
index fd43b9a..1403724 100644
--- a/src/engine/SCons/Script/__init__.py
+++ b/src/engine/SCons/Script/__init__.py
@@ -61,7 +61,6 @@ import SCons.Node.FS
 import SCons.Job
 from SCons.Errors import *
 import SCons.Sig
-import SCons.Sig.MD5
 from SCons.Taskmaster import Taskmaster
 import SCons.Builder
 import SCons.Script.SConscript
@@ -178,6 +177,7 @@ exit_status = 0 # exit status, assume success by default
 profiling = 0
 max_drift = None
 repositories = []
+sig_module = None
 
 #
 def print_it(text):
@@ -1040,9 +1040,14 @@ def _main():
 
     if not calc:
         if max_drift is not None:
-            SCons.Sig.default_calc = SCons.Sig.Calculator(SCons.Sig.MD5,
-                                                          max_drift)
-
+            if sig_module is not None:
+                SCons.Sig.default_calc = SCons.Sig.Calculator(module=sig_module,
+                                                              max_drift=max_drift)
+            else:
+                SCons.Sig.default_calc = SCons.Sig.Calculator(max_drift=max_drift)
+        elif sig_module is not None:
+            SCons.Sig.default_calc = SCons.Sig.Calculator(module=sig_module)
+            
         calc = SCons.Sig.default_calc
 
     display("scons: Building targets ...")
diff --git a/src/engine/SCons/Sig/TimeStamp.py b/src/engine/SCons/Sig/TimeStamp.py
index de0600d..997742d 100644
--- a/src/engine/SCons/Sig/TimeStamp.py
+++ b/src/engine/SCons/Sig/TimeStamp.py
@@ -63,6 +63,13 @@ def to_string(signature):
 
 def from_string(string):
     """Convert a string to a timestamp"""
-    return int(string)
+    try:
+        return int(string)
+    except ValueError:
+        # if the signature isn't an int, then
+        # the user probably just switched from
+        # MD5 signatures to timestamp signatures,
+        # so ignore the error:
+        return None
 
 
diff --git a/src/engine/SCons/Sig/__init__.py b/src/engine/SCons/Sig/__init__.py
index b6a5c25..9a4c846 100644
--- a/src/engine/SCons/Sig/__init__.py
+++ b/src/engine/SCons/Sig/__init__.py
@@ -36,6 +36,13 @@ import SCons.Node
 import time
 import SCons.Warnings
 
+try:
+    import MD5
+    default_module = MD5
+except ImportError:
+    import TimeStamp
+    default_module = TimeStamp
+
 #XXX Get rid of the global array so this becomes re-entrant.
 sig_files = []
 
@@ -265,14 +272,13 @@ class SConsignFile:
             except:
                 pass
 
-
 class Calculator:
     """
     Encapsulates signature calculations and .sconsign file generating
     for the build engine.
     """
 
-    def __init__(self, module=None, max_drift=2*24*60*60):
+    def __init__(self, module=default_module, max_drift=2*24*60*60):
         """
         Initialize the calculator.
 
@@ -281,17 +287,7 @@ class Calculator:
           cache content signatures. A negative value means to never cache
           content signatures. (defaults to 2 days)
         """
-        if module is None:
-            try:
-                import MD5
-                self.module = MD5
-            except ImportError:
-                # fallback on timestamp signatures if MD5 is not available
-                # XXX add a warning message here
-                import TimeStamp
-                self.module = TimeStamp
-        else:
-            self.module = module
+        self.module = module
         self.max_drift = max_drift
 
     def bsig(self, node):