Recognize non-changes in posted data server-side

This is a terrible kluge, but time doesn't permit modifying the
system.  All of this also touches old code that is untested, which is
difficult to modify with confidence.

* src/server/DocumentServer.js (DocumentServer#create): Use
  StagingBucket.
* src/server/Server.js: Remove logic now handled by DataProcessor.
* src/server/request/DataProcessor.js (processDiff): Wrap in
  StagingBucket to filter out values that do not result in changes.
* test/server/request/DataProcessorTest.js: Update failing cases.

src/server/DocumentServer.js

@@ -25,6 +25,7 @@ const {
     bucket: {
         bucket_filter,
         QuoteDataBucket,
+        StagingBucket,
     },
 
     dapi: {
@@ -67,7 +68,8 @@ module.exports = Class( 'DocumentServer',
                 ),
                 apis
             ),
-            DapiMetaSource( QuoteDataBucket )
+            DapiMetaSource( QuoteDataBucket ),
+            StagingBucket
         )
     ),
 } );

src/server/Server.js

@@ -1140,12 +1140,7 @@ module.exports = Class( 'Server' )
                         parsed_data, request, program, bucket
                     );
 
-                    quote.setData( filtered );
-
                     server._monitorMetadataPromise( quote, dapis );
-
-                    // calculated values (store only)
-                    program.initQuote( bucket, true );
                }
                 catch ( err )
                 {

src/server/request/DataProcessor.js

@@ -23,7 +23,7 @@
 
 const { Class }   = require( 'easejs' );
 
-const { QuoteDataBucket } = require( '../../' ).bucket;
+const { QuoteDataBucket, StagingBucket } = require( '../../' ).bucket;
 
 
 /**
@@ -56,15 +56,20 @@ module.exports = Class( 'DataProcessor',
     /**
      * Initialize processor
      *
-     * @param {Object}         filter      bucket filter
-     * @param {function()}     dapif       data API constructor
-     * @param {DapiMetaSource} meta_source metadata source
+     * The staging bucket constructor will be used to wrap the bucket for
+     * diff-related operations.
+     *
+     * @param {Object}           filter       bucket filter
+     * @param {function()}       dapif        data API constructor
+     * @param {DapiMetaSource}   meta_source  metadata source
+     * @param {function(Bucket)} staging_ctor staging bucket constructor
      */
-    constructor( filter, dapif, meta_source )
+    constructor( filter, dapif, meta_source, staging_ctor )
     {
-        this._filter     = filter;
-        this._dapif      = dapif;
-        this._metaSource = meta_source;
+        this._filter      = filter;
+        this._dapif       = dapif;
+        this._metaSource  = meta_source;
+        this._stagingCtor = staging_ctor;
     },
 
 
@@ -86,12 +91,21 @@ module.exports = Class( 'DataProcessor',
     {
         const filtered     = this.sanitizeDiff( data, request, program, false );
         const dapi_manager = this._dapif( program.apis, request );
+        const staging      = this._stagingCtor( bucket );
+
+        // forbidBypass will force diff generation on initQuote
+        staging.setValues( filtered, true );
+        staging.forbidBypass();
+
+        program.initQuote( staging, true );
 
         // array of promises for any dapi requests
         const dapis = this._triggerDapis(
-            dapi_manager, program, data, bucket
+            dapi_manager, program, staging.getDiff(), staging
         );
 
+        staging.commit();
+
         return {
             filtered: filtered,
             dapis:    dapis,

test/server/request/DataProcessorTest.js

@@ -90,7 +90,7 @@ describe( 'DataProcessor', () =>
             }
         };
 
-        Sut( filter, () => {}, meta_source )
+        Sut( filter, () => {}, meta_source, createStubStagingBucket )
             .processDiff( data, request, program );
 
         expect( data.filtered ).to.equal( true );
@@ -109,7 +109,7 @@ describe( 'DataProcessor', () =>
             done();
         }
 
-        Sut( filter, dapi_factory )
+        Sut( filter, dapi_factory, null, createStubStagingBucket )
             .processDiff( {}, request, program );
     } );
 
@@ -136,7 +136,12 @@ describe( 'DataProcessor', () =>
             meta_source,
         } = createStubs( false, {}, getFieldData );
 
-        const sut = Sut( filter, () => dapi_manager, meta_source );
+        const sut = Sut(
+            filter,
+            () => dapi_manager,
+            meta_source,
+            createStubStagingBucket
+        );
 
         program.meta.fields = {
             foo: {
@@ -249,7 +254,13 @@ function createSutFromStubs( /* see createStubs */ )
         program:      program,
         filter:       filter,
         meta_source:  meta_source,
-        sut:          Sut( filter, () => {}, meta_source ),
+
+        sut: Sut(
+            filter,
+            () => {},
+            meta_source,
+            createStubStagingBucket
+        ),
     };
 }
 
@@ -281,6 +292,8 @@ function createStubProgram( internals )
         internal: internals,
         meta:     { qtypes: {}, fields: {} },
         apis:     {},
+
+        initQuote() {},
     };
 }
 
@@ -305,3 +318,28 @@ function createStubBucket( data )
         },
     };
 }
+
+
+function createStubStagingBucket( bucket )
+{
+    let data = {};
+
+    return {
+        getDataByName( name )
+        {
+            return bucket.getDataByName( name );
+        },
+
+        setValues( values )
+        {
+            data = values;
+        },
+
+        forbidBypass() {},
+        getDiff()
+        {
+            return data;
+        },
+        commit() {},
+    };
+}