XD-1112 make read-only transaction freeze the session

entity-store/src/main/kotlin/jetbrains/exodus/entitystore/orientdb/OStoreTransactionImpl.kt

@@ -121,6 +121,16 @@ class OStoreTransactionImpl(
         check(session.isActiveOnCurrentThread) { "The session is not active on the current thread" }
         check(session.transaction is OTransactionNoTx) { "The session must not have a transaction" }
         try {
+            if (readOnly) {
+                /**
+                 * It is not enough to provide the best experience to the client code.
+                 * The session will throw an exception only on commit(), but not when
+                 * the client code creates/edits/deletes entities.
+                 *
+                 * So, we keep and check the readOnly flag too.
+                 */
+                session.freeze(true)
+            }
             session.begin()
             // initialize transaction id
             transactionIdImpl

entity-store/src/test/kotlin/jetbrains/exodus/entitystore/orientdb/OStoreTransactionLifecycleTest.kt

@@ -15,6 +15,8 @@
  */
 package jetbrains.exodus.entitystore.orientdb
 
+import com.orientechnologies.common.concur.lock.OModificationOperationProhibitedException
+import com.orientechnologies.orient.core.db.ODatabaseSession
 import com.orientechnologies.orient.core.metadata.schema.OClass
 import com.orientechnologies.orient.core.metadata.schema.OType
 import com.orientechnologies.orient.core.record.OVertex
@@ -57,7 +59,6 @@ class OStoreTransactionLifecycleTest : OTestMixin {
 
     @Test
     fun `commit() and abort() finish transaction`() {
-        orientDb.store.executeInTransaction {  }
         commitAbort.forEach { (terminalTxActionName, terminalTxAction) ->
             allTxActions.forEach { (txActionName, txAction) ->
             val tx = beginTransaction()
@@ -118,4 +119,16 @@ class OStoreTransactionLifecycleTest : OTestMixin {
             }
         }
     }
+
+    @Test
+    fun `read-only transaction freezes the session`() {
+        beginReadonlyTransaction()
+        val session = ODatabaseSession.getActiveSession() as ODatabaseSession
+
+        val v = session.newVertex()
+        v.save<OVertex>()
+        assertFailsWith<OModificationOperationProhibitedException> { session.commit() }
+
+        session.close()
+    }
 }

entity-store/src/test/kotlin/jetbrains/exodus/entitystore/orientdb/OTransactionLifecycleTest.kt

@@ -15,6 +15,7 @@
  */
 package jetbrains.exodus.entitystore.orientdb
 
+import com.orientechnologies.common.concur.lock.OModificationOperationProhibitedException
 import com.orientechnologies.orient.core.db.ODatabase.STATUS
 import com.orientechnologies.orient.core.exception.ODatabaseException
 import com.orientechnologies.orient.core.metadata.schema.OClass
@@ -38,6 +39,31 @@ class OTransactionLifecycleTest : OTestMixin {
 
     override val orientDb = orientDbRule
 
+    @Test
+    fun `session-freeze(true) makes the session read-only`() {
+        val session = orientDb.openSession()
+
+        session.freeze(true)
+
+        val v = session.newVertex()
+        assertFailsWith<OModificationOperationProhibitedException> { v.save<OVertex>() }
+
+        session.begin()
+        val v1 = session.newVertex()
+        v1.save<OVertex>()
+        assertFailsWith<OModificationOperationProhibitedException> { session.commit() }
+
+        // after release() we can write again
+        session.release()
+
+        session.begin()
+        val v2 = session.newVertex()
+        v2.save<OVertex>()
+        session.commit()
+
+        session.close()
+    }
+
     @Test
     fun `open, begin, commit, close - no changes`() {
         val session = orientDb.openSession()

entity-store/src/test/kotlin/jetbrains/exodus/entitystore/orientdb/testutil/OTestMixin.kt

@@ -41,6 +41,11 @@ interface OTestMixin {
         return store.beginTransaction() as OStoreTransactionImpl
     }
 
+    fun beginReadonlyTransaction(): OStoreTransactionImpl {
+        val store = orientDb.store
+        return store.beginReadonlyTransaction() as OStoreTransactionImpl
+    }
+
     fun <R> withStoreTx(block: (OStoreTransaction) -> R): R {
         return orientDb.withStoreTx(block)
     }