feat: Add functions to the Kv API in order to query ranges of keys and/or values #345 - check previous transaction finished

src/cache/SortKeyCache.ts

@@ -51,7 +51,7 @@ export interface SortKeyCache<V> {
 
   close(): Promise<void>;
 
-  begin(): void;
+  begin(): Promise<void>;
 
   rollback(): void;
 

src/cache/impl/LevelDbCache.ts

@@ -20,10 +20,12 @@ import { AbstractKeyIteratorOptions } from 'abstract-level/types/abstract-iterat
  */
 
 class ClientValueWrapper<V> {
-  constructor(readonly value: V, readonly tombstone: boolean = false) {}
+  constructor(readonly value: V, readonly tomb: boolean = false) {}
 }
 
 export class LevelDbCache<V> implements SortKeyCache<V> {
+  private readonly ongoingTransactionMark = '$$warp-internal-transaction$$';
+
   private readonly logger = LoggerFactory.INST.create('LevelDbCache');
   private readonly subLevelSeparator: string;
   private readonly subLevelOptions: AbstractSublevelOptions<string, ClientValueWrapper<V>>;
@@ -79,7 +81,12 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
     await contractCache.open();
     try {
       const result: ClientValueWrapper<V> = await contractCache.get(cacheKey.sortKey);
-      const resultValue = result.tombstone ? null : result.value;
+      let resultValue: V;
+      if (result.tomb === undefined && result.value === undefined) {
+        resultValue = result as V;
+      } else {
+        resultValue = result.tomb ? null : result.value;
+      }
       return new SortKeyCacheResult<V>(cacheKey.sortKey, resultValue);
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
     } catch (e: any) {
@@ -98,7 +105,10 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
     const keys = await contractCache.keys({ reverse: true, limit: 1 }).all();
     if (keys.length) {
       const lastValueWrap = await contractCache.get(keys[0]);
-      if (!lastValueWrap.tombstone) {
+      if (lastValueWrap.tomb === undefined && lastValueWrap.value === undefined) {
+        return new SortKeyCacheResult<V>(keys[0], lastValueWrap as V);
+      }
+      if (!lastValueWrap.tomb) {
         return new SortKeyCacheResult<V>(keys[0], lastValueWrap.value);
       }
     }
@@ -112,7 +122,7 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
     const keys = await contractCache.keys({ reverse: true, lte: sortKey, limit: 1 }).all();
     if (keys.length) {
       const cachedVal = await contractCache.get(keys[0]);
-      if (!cachedVal.tombstone) {
+      if (!cachedVal.tomb) {
         return new SortKeyCacheResult<V>(keys[0], cachedVal.value);
       }
     }
@@ -124,7 +134,7 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
   }
 
   /**
-   * Delete operation under the hood is a write operation with setting tombstone flag to true.
+   * Delete operation under the hood is a write operation with setting tomb flag to true.
    * The idea behind is based on Cassandra Tombstone
    * https://www.instaclustr.com/support/documentation/cassandra/using-cassandra/managing-tombstones-in-cassandra/
    * There is a couple of benefits to this approach:
@@ -142,11 +152,10 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
     // manually opening to fix https://github.com/Level/level/issues/221
     await contractCache.open();
     await contractCache.put(stateCacheKey.sortKey, valueWrapper);
-    if (!this._rollbackBatch) {
-      this.begin();
-    }
+    if (this._rollbackBatch) {
       this._rollbackBatch.del(stateCacheKey.sortKey, { sublevel: contractCache });
     }
+  }
 
   async delete(key: string): Promise<void> {
     const contractCache = this.db.sublevel<string, ClientValueWrapper<V>>(key, this.subLevelOptions);
@@ -166,7 +175,6 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
 
   async open(): Promise<void> {
     await this.db.open();
-    await this.begin();
   }
 
   async close(): Promise<void> {
@@ -175,20 +183,53 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
     }
   }
 
-  begin() {
-    this._rollbackBatch = this.db.batch();
+  async begin(): Promise<void> {
+    await this.initRollbackBatch();
   }
 
   async rollback() {
-    if (this._rollbackBatch && this._rollbackBatch.length > 0) {
+    if (this._rollbackBatch) {
+      this._rollbackBatch.del(this.ongoingTransactionMark);
       await this._rollbackBatch.write();
+      await this._rollbackBatch.close();
+    }
+    this._rollbackBatch = null;
+  }
+
+  private async initRollbackBatch(): Promise<
+    AbstractChainedBatch<MemoryLevel<string, ClientValueWrapper<V>>, string, ClientValueWrapper<V>>
+  > {
+    if (this._rollbackBatch == null) {
+      await this.checkPreviousTransactionFinished();
+      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+      // @ts-ignore
+      await this.db.put(this.ongoingTransactionMark, 'ongoing');
+
+      this._rollbackBatch = this.db.batch();
+    }
+    return this._rollbackBatch;
+  }
+
+  private async checkPreviousTransactionFinished() {
+    let transactionMarkValue;
+
+    try {
+      transactionMarkValue = await this.db.get(this.ongoingTransactionMark);
+      // eslint-disable-next-line no-empty
+    } catch (error) {}
+
+    if (transactionMarkValue == 'ongoing') {
+      throw new Error(`Database seems to be in inconsistent state. The previous transaction has not finished.`);
     }
   }
 
   async commit() {
     if (this._rollbackBatch) {
-      await this._rollbackBatch.clear().close();
+      await this._rollbackBatch.clear();
+      await this.db.del(this.ongoingTransactionMark);
+      await this._rollbackBatch.close();
     }
+    this._rollbackBatch = null;
   }
 
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -207,7 +248,7 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
     for (const joinedKey of keys) {
       // default joined key format used by sub-levels:
       // <separator><contract_tx_id (43 chars)><separator><sort_key>
-      const sortKey = joinedKey.substring(45);
+      const sortKey = joinedKey.split(this.subLevelSeparator)[1];
       if (sortKey.localeCompare(lastSortKey) > 0) {
         lastSortKey = sortKey;
       }
@@ -221,6 +262,9 @@ export class LevelDbCache<V> implements SortKeyCache<V> {
   }
 
   validateKey(key: string) {
+    if (key.includes(this.ongoingTransactionMark)) {
+      throw new Error(`Validation error: Key ${key} for internal use only`);
+    }
     if (key.includes(this.subLevelSeparator)) {
       throw new Error(`Validation error: key ${key} contains db separator ${this.subLevelSeparator}`);
     }

src/contract/states/ContractInteractionState.ts

@@ -49,7 +49,8 @@ export class ContractInteractionState implements InteractionState {
 
   async commit(interaction: GQLNodeInterface): Promise<void> {
     if (interaction.dry) {
-      return await this.rollbackKVs();
+      await this.rollbackKVs();
+      return this.reset();
     }
     try {
       await this.doStoreJson(this._json, interaction);

src/core/modules/impl/handler/JsHandlerApi.ts

@@ -134,6 +134,7 @@ export class JsHandlerApi<State> extends AbstractContractHandler<State> {
 
     try {
       await this.swGlobal.kv.open();
+      await this.swGlobal.kv.begin();
 
       const handlerResult = await Promise.race([timeoutPromise, this.contractFunction(stateClone, interaction)]);
 

src/core/modules/impl/handler/WasmHandlerApi.ts

@@ -34,8 +34,16 @@ export class WasmHandlerApi<State> extends AbstractContractHandler<State> {
       this.assignWrite(executionContext);
 
       await this.swGlobal.kv.open();
+      await this.swGlobal.kv.begin();
       const handlerResult = await this.doHandle(interaction);
+
+      if (interactionData.interaction.interactionType === 'view') {
+        // view calls are not allowed to perform any KV modifications
+        await this.swGlobal.kv.rollback();
+      } else {
         await this.swGlobal.kv.commit();
+      }
+
       return {
         type: 'ok',
         result: handlerResult,
@@ -62,10 +70,6 @@ export class WasmHandlerApi<State> extends AbstractContractHandler<State> {
         };
       }
     } finally {
-      if (interactionData.interaction.interactionType === 'view') {
-        // view calls are not allowed to perform any KV modifications
-        await this.swGlobal.kv.rollback();
-      }
       await this.swGlobal.kv.close();
     }
   }

src/legacy/smartweave-global.ts

@@ -313,6 +313,12 @@ export class KV {
     return this._storage.kvMap(sortKey, options);
   }
 
+  async begin() {
+    if (this._storage) {
+      return this._storage.begin();
+    }
+  }
+
   async commit(): Promise<void> {
     if (this._storage) {
       if (this._transaction.dryRun) {