blockstore: add file block storage

lib/blockstore/abstract.js

@@ -0,0 +1,100 @@
+/*!
+ * blockstore/abstract.js - abstract block store for bcoin
+ * Copyright (c) 2019, Braydon Fuller (MIT License).
+ * https://github.com/bcoin-org/bcoin
+ */
+
+'use strict';
+
+const Logger = require('blgr');
+
+/**
+ * Abstract Block Store
+ *
+ * @alias module:blockstore.AbstractBlockStore
+ * @abstract
+ */
+
+class AbstractBlockStore {
+  /**
+   * Create an abstract blockstore.
+   * @constructor
+   */
+
+  constructor(options) {
+    this.options = options || {};
+
+    if (this.options.logger != null)
+      this.logger = this.options.logger.context('blockstore');
+    else
+      this.logger = Logger.global.context('blockstore');
+  }
+
+  /**
+   * This method opens any necessary resources and
+   * initializes the store to be ready to be queried.
+   * @returns {Promise}
+   */
+
+  async open() {
+    throw new Error('Abstract method.');
+  }
+
+  /**
+   * This method closes resources and prepares
+   * store to be closed.
+   * @returns {Promise}
+   */
+
+  async close() {
+    throw new Error('Abstract method.');
+  }
+
+  /**
+   * This method stores block data. The action should be idempotent.
+   * If the data is already stored, the behavior will be the same. Any
+   * concurrent requests to store the same data will produce the same
+   * result, and will not conflict with each other.
+   * @returns {Promise}
+   */
+
+  async write(hash, data) {
+    throw new Error('Abstract method.');
+  }
+
+  /**
+   * This method will retrieve block data. Smaller portions of
+   * the block can be read by using the offset and size arguments.
+   * @returns {Promise}
+   */
+
+  async read(hash, offset, size) {
+    throw new Error('Abstract method.');
+  }
+
+  /**
+   * This will free resources for storing the block data. This
+   * may not mean that the block is deleted, but that it should
+   * no longer consume any local storage resources.
+   * @returns {Promise}
+   */
+
+  async prune(hash) {
+    throw new Error('Abstract method.');
+  }
+
+  /**
+   * This will check if a block has been stored and is available.
+   * @returns {Promise}
+   */
+
+  async has(hash) {
+    throw new Error('Abstract method.');
+  }
+}
+
+/*
+ * Expose
+ */
+
+module.exports = AbstractBlockStore;