[ui] Add support for showing the values in the database.

 - This requires maintaining a manual Python port of the
   llbuild::buildsystem::BuildValue type, but unfortunately I don't have a
   better idea currently -- and being able to see the values is really important
   to debugging complex databases.

products/ui/llbuildui/model.py

@@ -1,3 +1,5 @@
+import struct
+
 from sqlalchemy import *
 from sqlalchemy.orm import relation, relationship
 from sqlalchemy.ext.declarative import declarative_base
@@ -22,7 +24,7 @@ class RuleResult(Base):
     id = Column(Integer, nullable=False, primary_key=True)
     key_id = Column(Integer, ForeignKey(KeyName.id),
                      nullable=False)
-    value = Column(Integer, nullable=False)
+    value_bytes = Column("value", Integer, nullable=False)
     built_at = Column(Integer, nullable=False)
     computed_at = Column(Integer, nullable=False)
 
@@ -34,6 +36,10 @@ def __repr__(self):
             self.__class__.__name__, (self.id, self.key, self.value,
                                       self.built_at, self.computed_at))
 
+    @property
+    def value(self):
+        return BuildValue(self.value_bytes)
+
 class RuleDependency(Base):
     __tablename__ = "rule_dependencies"
 
@@ -48,3 +54,98 @@ class RuleDependency(Base):
     def __repr__(self):
         return "%s%r" % (
             self.__class__.__name__, (self.rule_id, self.key))
+
+###
+
+class BuildValue(object):
+    # FIXME: This is a manually Python translation of the C++
+    # llbuild::buildsystem::BuildValue type, which is unfortunate, but it isn't
+    # available via an API we can access directly yet.
+
+    kinds = [
+        "Invalid",
+        "VirtualInput", "ExistingInput", "MissingInput",
+        "DirectoryContents", "DirectoryTreeSignature",
+        "MissingOutput", "FailedInput",
+        "SuccessfulCommand", "FailedCommand",
+        "PropagatedFailureCommand", "CancelledCommand", "SkippedCommand",
+        "Target",
+    ]
+
+    def __init__(self, data):
+        bytes = str(data)
+
+        # The first byte is the kind.
+        if bytes:
+            self.kind = self.__class__.kinds[struct.unpack("<B", bytes[0])[0]]
+            bytes = bytes[1:]
+        else:
+            self.kind = "Invalid"
+
+        # The next item is the signature, if used.
+        if self.hasCommandSignature:
+            self.signature = struct.unpack("<Q", bytes[:8])[0]
+            bytes = bytes[8:]
+        else:
+            self.signature = None
+
+        # The outputs follow, if used.
+        if self.hasOutputInfo:
+            numOutputs = struct.unpack("<I", bytes[:4])[0]
+            bytes = bytes[4:]
+            self.outputs = []
+            for i in range(numOutputs):
+                # Read the file information.
+                self.outputs.append(FileInfo(bytes[:48]))
+                bytes = bytes[48:]
+        else:
+            self.outputs = None
+
+        # The strings follow, if used.
+        if self.hasStringList:
+            stringsLength = struct.unpack("<Q", bytes[:8])[0]
+            bytes = bytes[8:]
+            stringData = bytes[:stringsLength]
+            bytes = bytes[stringsLength:]
+            assert len(stringData) == stringsLength
+            assert stringData[-1] == '\0'
+            self.strings = stringData[:-1].split("\0")
+        else:
+            self.strings = None
+
+        assert len(bytes) == 0
+
+    @property
+    def hasCommandSignature(self):
+        return self.kind in ("SuccessfulCommand", "DirectoryTreeSignature")
+
+    @property
+    def hasStringList(self):
+        return self.kind in ("DirectoryContents",)
+
+    @property
+    def hasOutputInfo(self):
+        return self.kind in ("ExistingInput", "SuccessfulCommand",
+                             "DirectoryContents")
+
+    def __repr__(self):
+        output = "BuildValue(kind=%r" % self.kind
+        if self.signature is not None:
+            output += ", signature=%0x" % self.signature
+        if self.outputs is not None:
+            output += ", outputs=%r" % self.outputs
+        if self.strings is not None:
+            output += ", strings=%r" % self.strings
+        output += ")"
+        return output
+
+class FileInfo(object):
+    def __init__(self, bytes):
+        (self.device, self.inode, self.mode, self.size,
+         modTimeSec, modTimeNano) = struct.unpack("<QQQQQQ", bytes)
+        self.modTime =  (modTimeSec, modTimeNano)
+
+    def __repr__(self):
+        return "FileInfo(device=%r, inode=%#0x, mode=%r, size=%r, mtime=(%r, %r))" % (
+            self.device, self.inode, self.mode, self.size,
+            self.modTime[0], self.modTime[1])

products/ui/llbuildui/templates/rule_result.html

@@ -18,4 +18,7 @@ <h4>Dependents</h4>
 </a><br>
 {% endfor %}
 
+<h4>Value</h4>
+{{ rule_result.value }}
+
 {% endblock %}