Improve efficiency of incremental manifest build.

Move the file.copy check before the manifest lookup to save a lookup and (probably) find for zero-length files when bundling.

This also removes a layer of indentation which helps with readability.

src/info/manifest.c

@@ -1686,35 +1686,32 @@ manifestBuildIncr(
         {
             ManifestFile file = manifestFile(this, fileIdx);
 
-            // Check if a prior file exists
+            // Check if a prior file exists for files that will be copied (i.e. not zero-length files when bundling). If a prior
-            if (manifestFileExists(manifestPrior, file.name))
+            // file does exist it may be possible to reference it instead of copying the file.
+            if (file.copy && manifestFileExists(manifestPrior, file.name))
             {
                 const ManifestFile filePrior = manifestFileFind(manifestPrior, file.name);
 
-                // If the file will be copied then preserve values from the prior file when needed. Some files may have been
+                // If file size is equal to prior size then the file can be referenced instead of copied if it has not changed (this
-                // designated not to be copied at manifest build time, e.g. zero-length files when bundling.
+                // must be determined during the backup).
-                if (file.copy)
-                {
-                    // If file size is equal to prior size then the file can be referenced instead of copied if it has not changed
-                    // (this must be determined during the backup).
                 const bool fileSizeEqual = file.size == filePrior.size;
 
                 // If prior file was stored with block incremental and file size is at least prior file block size then preserve
-                    // prior values. If file size is less than prior file block size then the entire file will need to be stored and
+                // prior values. If file size is less than prior file block size then the entire file will need to be stored and the
-                    // the map will be useless as long as the file stays at this size. It is not possible to change the block size
+                // map will be useless as long as the file stays at this size. It is not possible to change the block size in a
-                    // in a backup set and the map info will be required to compare against the prior block incremental.
+                // backup set and the map info will be required to compare against the prior block incremental.
                 const bool fileBlockIncrPreserve = filePrior.blockIncrMapSize > 0 && file.size >= filePrior.blockIncrSize;
 
                 // Perform delta if enabled and file size is equal to prior but not zero. Files of unequal length are always
-                    // different while zero-length files are always the same, so it wastes time to check them. It is possible for
+                // different while zero-length files are always the same, so it wastes time to check them. It is possible for a file
-                    // a file to be truncated down to equal the prior file during backup, but the overhead of checking for such an
+                // to be truncated down to equal the prior file during backup, but the overhead of checking for such an unlikely
-                    // unlikely event does not seem worth the possible space saved.
+                // event does not seem worth the possible space saved.
                 file.delta = delta && fileSizeEqual && file.size != 0;
 
-                    // Do not copy if size and prior size are both zero. Zero-length files are always equal so the file can simply
+                // Do not copy if size and prior size are both zero. Zero-length files are always equal so the file can simply be
-                    // be referenced to the prior file. Note that this is only for the case where zero-length files are being
+                // referenced to the prior file. Note that this is only for the case where zero-length files are being explicitly
-                    // explicitly written to the repo. Bundled zero-length files disable copy at manifest build time and never
+                // written to the repo. Bundled zero-length files disable copy at manifest build time and never reference the prior
-                    // reference the prior file, even if it is also zero-length.
+                // file, even if it is also zero-length.
                 if (file.size == 0 && filePrior.size == 0)
                     file.copy = false;
 
@@ -1726,9 +1723,9 @@ manifestBuildIncr(
                 ASSERT(file.copy || fileSizeEqual);
                 ASSERT(!file.delta || fileSizeEqual);
 
-                    // Preserve values if the file will not be copied, is possibly equal to the prior file, or will be stored with
+                // Preserve values if the file will not be copied, is possibly equal to the prior file, or will be stored with block
-                    // block incremental and the prior file is also stored with block incremental. If the file will not be copied
+                // incremental and the prior file is also stored with block incremental. If the file will not be copied then the
-                    // then the file size must be equal to the prior file so there is no need to check that condition separately.
+                // file size must be equal to the prior file so there is no need to check that condition separately.
                 if (fileSizeEqual || fileBlockIncrPreserve)
                 {
                     file.sizePrior = filePrior.size;
@@ -1762,7 +1759,6 @@ manifestBuildIncr(
             }
         }
     }
-    }
     MEM_CONTEXT_TEMP_END();
 
     FUNCTION_LOG_RETURN_VOID();