feat(model-client): added IModelClientV2.pollHash

After adding .pullHash it was just inconsistent to not have a .pollHash.

Author: slisson

model-client/src/commonMain/kotlin/org/modelix/model/client2/IModelClientV2.kt

@@ -55,5 +55,11 @@ interface IModelClientV2 {
 
     suspend fun pullHash(branch: BranchReference): String
 
+    /**
+     * While `pull` returns immediately `poll` returns as soon as a new version, that is different from the given
+     * `lastKnownVersion`, is pushed to the server or after some timout specified by the server (usually ~30 seconds).
+     */
     suspend fun poll(branch: BranchReference, lastKnownVersion: IVersion?): IVersion
+
+    suspend fun pollHash(branch: BranchReference, lastKnownVersion: IVersion?): String
 }

model-client/src/commonMain/kotlin/org/modelix/model/client2/ModelClientV2.kt

@@ -173,7 +173,20 @@ class ModelClientV2(
             }
         }
         val receivedHash: String = response.body()
-//        LOG.debug { "${clientId.toString(16)}.pullHash($branch) -> $receivedHash" }
+        return receivedHash
+    }
+
+    override suspend fun pollHash(branch: BranchReference, lastKnownVersion: IVersion?): String {
+        val response = httpClient.get {
+            url {
+                takeFrom(baseUrl)
+                appendPathSegmentsEncodingSlash("repositories", branch.repositoryId.id, "branches", branch.branchName, "pollHash")
+                if (lastKnownVersion != null) {
+                    parameters["lastKnown"] = lastKnownVersion.getContentHash()
+                }
+            }
+        }
+        val receivedHash: String = response.body()
         return receivedHash
     }
 

model-server/src/main/kotlin/org/modelix/model/server/handlers/ModelReplicationServer.kt

@@ -150,6 +150,11 @@ class ModelReplicationServer(val repositoriesManager: RepositoriesManager) {
                             val newVersionHash = repositoriesManager.pollVersionHash(branchRef(), lastKnownVersionHash)
                             call.respondDelta(newVersionHash, lastKnownVersionHash)
                         }
+                        get("pollHash") {
+                            val lastKnownVersionHash = call.request.queryParameters["lastKnown"]
+                            val newVersionHash = repositoriesManager.pollVersionHash(branchRef(), lastKnownVersionHash)
+                            call.respondText(newVersionHash)
+                        }
                         webSocket("listen") {
                             var lastVersionHash = call.request.queryParameters["lastKnown"]
                             while (coroutineContext[Job]?.isCancelled == false) {