Pass commit IDs into DiffInfo

This change enables logging file access by commit ID and path using
the AuditListener interface. After a GetDiff REST request is processed,
the AuditListener.onAuditableAction method is called with an
ExtendedHttpAuditEvent parameter, which in turn references a DiffInfo
object. However, the diff base commit ID is not available anywhere in
this object graph. Left and right commit IDs are available in the
PatchScriptBuilder object; that is the data we need. This change
propagates the commit IDs through a series of intermediate data
structures and ultimately makes them available as transient fields in
the DiffInfo object. The AuditListener implementation will copy these
commit values into the access log, along with the file path, timestamp
and other typical logging fields.

The new fields are marked transient--unsupported
and undocumented. There are no anticipated side-effects.

Change-Id: I43e5a14e8951442039bd2d8e941e2aa128e82447

gerrit-common/src/main/java/com/google/gerrit/common/data/PatchScript.java

@@ -57,6 +57,8 @@ public class PatchScript {
   protected boolean intralineFailure;
   protected boolean intralineTimeout;
   protected boolean binary;
+  protected transient String commitIdA;
+  protected transient String commitIdB;
 
   public PatchScript(final Change.Key ck, final ChangeType ct, final String on,
       final String nn, final FileMode om, final FileMode nm,
@@ -65,7 +67,8 @@ public class PatchScript {
       final List<Edit> e, final DisplayMethod ma, final DisplayMethod mb,
       final String mta, final String mtb, final CommentDetail cd,
       final List<Patch> hist, final boolean hf, final boolean id,
-      final boolean idf, final boolean idt, boolean bin) {
+      final boolean idf, final boolean idt, boolean bin,
+      final String cma, final String cmb) {
     changeId = ck;
     changeType = ct;
     oldName = on;
@@ -88,6 +91,8 @@ public class PatchScript {
     intralineFailure = idf;
     intralineTimeout = idt;
     binary = bin;
+    commitIdA = cma;
+    commitIdB = cmb;
   }
 
   protected PatchScript() {
@@ -200,4 +205,12 @@ public class PatchScript {
   public boolean isBinary() {
     return binary;
   }
+
+  public String getCommitIdA() {
+    return commitIdA;
+  }
+
+  public String getCommitIdB() {
+    return commitIdB;
+  }
 }

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/common/DiffInfo.java

@@ -42,6 +42,8 @@ public class DiffInfo {
   }
 
   public static class FileMeta {
+    // The ID of the commit containing the file
+    public transient String commitId;
     // The name of the file
     public String name;
     // The content type of the file

gerrit-server/src/main/java/com/google/gerrit/server/change/GetDiff.java

@@ -201,6 +201,7 @@ public class GetDiff implements RestReadView<FileResource> {
           result.metaA.lines = ps.getA().size();
           result.metaA.webLinks =
               getFileWebLinks(state.getProject(), revA, result.metaA.name);
+          result.metaA.commitId = content.commitIdA;
         }
 
         if (ps.getDisplayMethodB() != DisplayMethod.NONE) {
@@ -211,6 +212,7 @@ public class GetDiff implements RestReadView<FileResource> {
           result.metaB.lines = ps.getB().size();
           result.metaB.webLinks =
               getFileWebLinks(state.getProject(), revB, result.metaB.name);
+          result.metaB.commitId = content.commitIdB;
         }
 
         if (intraline) {
@@ -264,6 +266,8 @@ public class GetDiff implements RestReadView<FileResource> {
     final SparseFileContent fileA;
     final SparseFileContent fileB;
     final boolean ignoreWS;
+    final String commitIdA;
+    final String commitIdB;
 
     int nextA;
     int nextB;
@@ -273,6 +277,8 @@ public class GetDiff implements RestReadView<FileResource> {
       fileA = ps.getA();
       fileB = ps.getB();
       ignoreWS = ps.isIgnoreWhitespace();
+      commitIdA = ps.getCommitIdA();
+      commitIdB = ps.getCommitIdB();
     }
 
     void addCommon(int end) {

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchScriptBuilder.java

@@ -214,7 +214,9 @@ class PatchScriptBuilder {
         a.displayMethod, b.displayMethod, a.mimeType.toString(),
         b.mimeType.toString(), comments, history, hugeFile,
         intralineDifferenceIsPossible, intralineFailure, intralineTimeout,
-        content.getPatchType() == Patch.PatchType.BINARY);
+        content.getPatchType() == Patch.PatchType.BINARY,
+        aId == null ? null : aId.getName(),
+        bId == null ? null : bId.getName());
   }
 
   private static boolean isModify(PatchListEntry content) {