Configure swap compression method: bzip2 or gzip

services/git-bridge/conf/example_config.json

@@ -26,6 +26,7 @@
         "minProjects": 50,
         "lowGiB": 128,
         "highGiB": 256,
-        "intervalMillis": 3600000
+        "intervalMillis": 3600000,
+        "compressionMethod": "bzip2"
     }
 }

services/git-bridge/conf/local.json

@@ -22,6 +22,7 @@
         "minProjects": 50,
         "lowGiB": 128,
         "highGiB": 256,
-        "intervalMillis": 3600000
+        "intervalMillis": 3600000,
+        "compressionMethod": "bzip2"
     }
 }

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/swap/job/SwapJob.java

@@ -13,6 +13,46 @@ import java.util.Optional;
  */
 public interface SwapJob {
 
+    enum CompressionMethod { Bzip2, Gzip }
+
+    static CompressionMethod stringToCompressionMethod(String compressionString) {
+        if (compressionString == null) {
+            return null;
+        }
+        CompressionMethod result;
+        switch (compressionString) {
+            case "gzip":
+                result = CompressionMethod.Gzip;
+                break;
+            case "bzip2":
+                result = CompressionMethod.Bzip2;
+                break;
+            default:
+                result = null;
+                break;
+        }
+        return result;
+    }
+
+    static String compressionMethodAsString(CompressionMethod compressionMethod) {
+        if (compressionMethod == null) {
+            return null;
+        }
+        String result;
+        switch (compressionMethod) {
+            case Gzip:
+                result =  "gzip";
+                break;
+            case Bzip2:
+                result =  "bzip2";
+                break;
+            default:
+                result =  null;
+                break;
+        }
+        return result;
+    }
+
     static SwapJob fromConfig(
             Optional<SwapJobConfig> cfg,
             ProjectLock lock,

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/swap/job/SwapJobConfig.java

@@ -1,5 +1,8 @@
 package uk.ac.ic.wlgitbridge.bridge.swap.job;
 
+import uk.ac.ic.wlgitbridge.util.Log;
+import uk.ac.ic.wlgitbridge.bridge.swap.job.SwapJob.CompressionMethod;
+
 /**
  * Created by winston on 23/08/2016.
  */
@@ -9,17 +12,20 @@ public class SwapJobConfig {
     private final int lowGiB;
     private final int highGiB;
     private final long intervalMillis;
+    private final String compressionMethod;
 
     public SwapJobConfig(
             int minProjects,
             int lowGiB,
             int highGiB,
-            long intervalMillis
+            long intervalMillis,
+            String compressionMethod
     ) {
         this.minProjects = minProjects;
         this.lowGiB = lowGiB;
         this.highGiB = highGiB;
         this.intervalMillis = intervalMillis;
+        this.compressionMethod = compressionMethod;
     }
 
     public int getMinProjects() {
@@ -38,4 +44,12 @@ public class SwapJobConfig {
         return intervalMillis;
     }
 
+    public SwapJob.CompressionMethod getCompressionMethod() {
+      CompressionMethod result = SwapJob.stringToCompressionMethod(compressionMethod);
+      if (result == null) {
+        Log.info("SwapJobConfig: un-supported compressionMethod '{}', default to 'bzip2'", compressionMethod);
+        result = CompressionMethod.Bzip2;
+      }
+      return result;
+    }
 }