chain: add interactive scan.

lib/blockchain/chain.js

@@ -28,6 +28,7 @@ const {OwnershipProof} = require('../covenants/ownership');
 const AirdropProof = require('../primitives/airdropproof');
 const {CriticalError} = require('../errors');
 const thresholdStates = common.thresholdStates;
+const scanAction = common.scanAction;
 const {states} = NameState;
 
 const {
@@ -2250,7 +2251,7 @@ class Chain extends AsyncEmitter {
 
   /**
    * Scan the blockchain for transactions containing specified address hashes.
-   * @param {Hash} start - Block hash to start at.
+   * @param {Hash|Number} start - Block hash or height to start at.
    * @param {Bloom} filter - Bloom filter containing tx and address hashes.
    * @param {Function} iter - Iterator.
    * @returns {Promise}
@@ -2265,6 +2266,78 @@ class Chain extends AsyncEmitter {
     }
   }
 
+  /**
+   * Interactive scan the blockchain for transactions containing specified
+   * address hashes. Allows repeat and abort.
+   * @param {Hash|Number} start - Block hash or height to start at.
+   * @param {BloomFilter} filter - Starting bloom filter containing tx,
+   * address and name hashes.
+   * @param {Function} iter - Iterator.
+   */
+
+  async scanInteractive(start, filter, iter) {
+    if (start == null)
+      start = this.network.genesis.hash;
+
+    if (typeof start === 'number')
+      this.logger.info('Scanning(interactive) from height %d.', start);
+    else
+      this.logger.info('Scanning(interactive) from block %x.', start);
+
+    let hash = start;
+
+    while (hash != null) {
+      const unlock = await this.locker.lock();
+
+      try {
+        const {entry, txs} = await this.db.scanBlock(hash, filter);
+
+        const action = await iter(entry, txs);
+
+        if (!action || typeof action !== 'object')
+          throw new Error('Did not get proper action');
+
+        switch (action.type) {
+          case scanAction.REPEAT: {
+            break;
+          }
+          case scanAction.REPEAT_SET: {
+            // try again with updated filter.
+            filter = action.filter;
+            break;
+          }
+          case scanAction.REPEAT_ADD: {
+            if (!filter)
+              throw new Error('No filter set.');
+
+            for (const chunk of action.chunks)
+              filter.add(chunk);
+            break;
+          }
+          case scanAction.NEXT: {
+            const next = await this.getNext(entry);
+            hash = next && next.hash;
+            break;
+          }
+          case scanAction.ABORT: {
+            this.logger.info('Scan(interactive) aborted at %x (%d).',
+              entry.hash, entry.height);
+            throw new Error('scan request aborted.');
+          }
+          default:
+            this.logger.debug('Scan(interactive) aborting. Unknown action: %d',
+              action.type);
+            throw new Error('Unknown action.');
+        }
+      } catch (e) {
+        this.logger.debug('Scan(interactive) errored. Error: %s', e.message);
+        throw e;
+      } finally {
+        unlock();
+      }
+    }
+  }
+
   /**
    * Add a block to the chain, perform all necessary verification.
    * @param {Block} block

lib/blockchain/chaindb.js

@@ -1612,6 +1612,51 @@ class ChainDB {
     this.logger.info('Finished scanning %d blocks.', total);
   }
 
+  /**
+   * Interactive scans block checks.
+   * @param {Hash|Number} blockID - Block hash or height to start at.
+   * @param {BloomFilter} [filter] - Starting bloom filter containing tx,
+   * address and name hashes.
+   * @returns {Promise}
+   */
+
+  async scanBlock(blockID, filter) {
+    assert(blockID);
+
+    const entry = await this.getEntry(blockID);
+
+    if (!entry)
+      throw new Error('Could not find entry.');
+
+    if (!await this.isMainChain(entry))
+      throw new Error('Cannot rescan an alternate chain.');
+
+    const block = await this.getBlock(entry.hash);
+
+    if (!block)
+      throw new Error('Block not found.');
+
+    this.logger.info(
+      'Scanning block %x (%d)',
+      entry.hash, entry.height);
+
+    let txs = [];
+
+    if (!filter) {
+      txs = block.txs;
+    } else {
+      for (const tx of block.txs) {
+        if (tx.testAndMaybeUpdate(filter))
+          txs.push(tx);
+      }
+    }
+
+    return {
+      entry,
+      txs
+    };
+  }
+
   /**
    * Save an entry to the database and optionally
    * connect it as the tip. Note that this method

lib/blockchain/common.js

@@ -69,3 +69,18 @@ exports.flags = {
 exports.flags.DEFAULT_FLAGS = 0
   | exports.flags.VERIFY_POW
   | exports.flags.VERIFY_BODY;
+
+/**
+ * Interactive scan actions.
+ * @enum {Number}
+ * @default
+ */
+
+exports.scanAction = {
+  NONE: 0,
+  ABORT: 1,
+  NEXT: 2,
+  REPEAT_SET: 3,
+  REPEAT_ADD: 4,
+  REPEAT: 5
+};

lib/node/fullnode.js

@@ -364,6 +364,18 @@ class FullNode extends Node {
     return this.chain.scan(start, filter, iter);
   }
 
+  /**
+   * Interactive rescan for any missed transactions.
+   * @param {Number|Hash} start - Start block.
+   * @param {Bloom} filter
+   * @param {Function} iter - Iterator.
+   * @returns {Promise}
+   */
+
+  scanInteractive(start, filter, iter) {
+    return this.chain.scanInteractive(start, filter, iter);
+  }
+
   /**
    * Broadcast a transaction.
    * @param {TX|Block|Claim|AirdropProof} item