add merkle and tx lru caches to BlockchainReaderService

-updates batched `HubDB.get_transactions_and_merkles` to use and set new lru caches
-caches txs from new blocks in anticipation of those txs being requested soon
-removes _tx_and_merkle_cache
-fixes metrics namespace

scribe/db/db.py

@@ -12,6 +12,7 @@ from functools import partial
 from bisect import bisect_right
 from collections import defaultdict
 from concurrent.futures.thread import ThreadPoolExecutor
+from scribe import PROMETHEUS_NAMESPACE
 from scribe.error import ResolveCensoredError
 from scribe.schema.url import URL, normalize_name
 from scribe.schema.claim import guess_stream_type
@@ -29,6 +30,7 @@ from scribe.db.prefixes import HashXMempoolStatusPrefixRow
 TXO_STRUCT = struct.Struct(b'>LH')
 TXO_STRUCT_unpack = TXO_STRUCT.unpack
 TXO_STRUCT_pack = TXO_STRUCT.pack
+NAMESPACE = f"{PROMETHEUS_NAMESPACE}_db"
 
 
 class HubDB:
@@ -79,14 +81,17 @@ class HubDB:
         self.tx_counts = None
         self.headers = None
         self.block_hashes = None
-        self.encoded_headers = LRUCacheWithMetrics(1 << 21, metric_name='encoded_headers', namespace='wallet_server')
+        self.encoded_headers = LRUCacheWithMetrics(1 << 21, metric_name='encoded_headers', namespace=NAMESPACE)
         self.last_flush = time.time()
 
         # Header merkle cache
         self.merkle = Merkle()
         self.header_mc = MerkleCache(self.merkle, self.fs_block_hashes)
 
-        self._tx_and_merkle_cache = LRUCacheWithMetrics(2 ** 16, metric_name='tx_and_merkle', namespace="wallet_server")
+        # lru cache of tx_hash: (tx_bytes, tx_num, position, tx_height)
+        self.tx_cache = LRUCacheWithMetrics(2 ** 14, metric_name='tx', namespace=NAMESPACE)
+        # lru cache of block heights to merkle trees of the block tx hashes
+        self.merkle_cache = LRUCacheWithMetrics(2 ** 15, metric_name='merkle', namespace=NAMESPACE)
 
         # these are only used if the cache_all_tx_hashes setting is on
         self.total_transactions: List[bytes] = []
@@ -98,6 +103,7 @@ class HubDB:
 
         self.genesis_bytes = bytes.fromhex(self.coin.GENESIS_HASH)
 
+
     def get_claim_from_txo(self, tx_num: int, tx_idx: int) -> Optional[TXOToClaimValue]:
         claim_hash_and_name = self.prefix_db.txo_to_claim.get(tx_num, tx_idx)
         if not claim_hash_and_name:
@@ -988,28 +994,36 @@ class HubDB:
     def get_block_txs(self, height: int) -> List[bytes]:
         return self.prefix_db.block_txs.get(height).tx_hashes
 
-    async def get_transactions_and_merkles(self, tx_hashes: Iterable[str]):
+    async def get_transactions_and_merkles(self, txids: List[str]):
         tx_infos = {}
-        needed = []
+        needed_tx_nums = []
         needed_confirmed = []
         needed_mempool = []
+        cached_mempool = []
+        needed_heights = set()
+        tx_heights_and_positions = defaultdict(list)
+
         run_in_executor = asyncio.get_event_loop().run_in_executor
 
-        for tx_hash in tx_hashes:
+        for txid in txids:
-            cached_tx = self._tx_and_merkle_cache.get(tx_hash)
+            tx_hash_bytes = bytes.fromhex(txid)[::-1]
+            cached_tx = self.tx_cache.get(tx_hash_bytes)
             if cached_tx:
-                tx, merkle = cached_tx
+                tx, tx_num, tx_pos, tx_height = cached_tx
-                tx_infos[tx_hash] = None if not tx else tx.hex(), merkle
+                if tx_height > 0:
+                    needed_heights.add(tx_height)
+                    tx_heights_and_positions[tx_height].append((tx_hash_bytes, tx, tx_num, tx_pos))
+                else:
+                    cached_mempool.append((tx_hash_bytes, tx))
             else:
-                tx_hash_bytes = bytes.fromhex(tx_hash)[::-1]
                 if self._cache_all_tx_hashes and tx_hash_bytes in self.tx_num_mapping:
                     needed_confirmed.append((tx_hash_bytes, self.tx_num_mapping[tx_hash_bytes]))
                 else:
-                    needed.append(tx_hash_bytes)
+                    needed_tx_nums.append(tx_hash_bytes)
 
-        if needed:
+        if needed_tx_nums:
-            for tx_hash_bytes, v in zip(needed, await run_in_executor(
+            for tx_hash_bytes, v in zip(needed_tx_nums, await run_in_executor(
-                    self._executor, self.prefix_db.tx_num.multi_get, [(tx_hash,) for tx_hash in needed],
+                    self._executor, self.prefix_db.tx_num.multi_get, [(tx_hash,) for tx_hash in needed_tx_nums],
                     True, True)):
                 tx_num = None if v is None else v.tx_num
                 if tx_num is not None:
@@ -1019,8 +1033,6 @@ class HubDB:
                 await asyncio.sleep(0)
 
         if needed_confirmed:
-            needed_heights = set()
-            tx_heights_and_positions = defaultdict(list)
             for (tx_hash_bytes, tx_num), tx in zip(needed_confirmed, await run_in_executor(
                     self._executor, self.prefix_db.tx.multi_get, [(tx_hash,) for tx_hash, _ in needed_confirmed],
                     True, False)):
@@ -1028,36 +1040,43 @@ class HubDB:
                 needed_heights.add(tx_height)
                 tx_pos = tx_num - self.tx_counts[tx_height - 1]
                 tx_heights_and_positions[tx_height].append((tx_hash_bytes, tx, tx_num, tx_pos))
+                self.tx_cache[tx_hash_bytes] = tx, tx_num, tx_pos, tx_height
 
-            sorted_heights = list(sorted(needed_heights))
+        sorted_heights = list(sorted(needed_heights))
+        merkles: Dict[int, FastMerkleCacheItem] = {}   # uses existing cached merkle trees when they're available
+        needed_for_merkle_cache = []
+        for height in sorted_heights:
+            merkle = self.merkle_cache.get(height)
+            if merkle:
+                merkles[height] = merkle
+            else:
+                needed_for_merkle_cache.append(height)
+        if needed_for_merkle_cache:
             block_txs = await run_in_executor(
-                self._executor, self.prefix_db.block_txs.multi_get, [(height,) for height in sorted_heights]
+                self._executor, self.prefix_db.block_txs.multi_get,
+                [(height,) for height in needed_for_merkle_cache]
             )
-            block_txs = {height: v.tx_hashes for height, v in zip(sorted_heights, block_txs)}
+            for height, v in zip(needed_for_merkle_cache, block_txs):
-            for tx_height, v in tx_heights_and_positions.items():
+                merkles[height] = self.merkle_cache[height] = FastMerkleCacheItem(v.tx_hashes)
-                branches, root = self.merkle.branches_and_root(
-                    block_txs[tx_height], [tx_pos for (tx_hash_bytes, tx, tx_num, tx_pos) in v]
-                )
-                for (tx_hash_bytes, tx, tx_num, tx_pos) in v:
-                    merkle = {
-                        'block_height': tx_height,
-                        'merkle': [
-                            hash_to_hex_str(_hash)
-                            for _hash in branches[tx_pos]
-                        ],
-                        'pos': tx_pos
-                    }
-                    tx_infos[tx_hash_bytes[::-1].hex()] = None if not tx else tx.hex(), merkle
-                    if tx_height > 0 and tx_height + 10 < self.db_height:
-                        self._tx_and_merkle_cache[tx_hash_bytes[::-1].hex()] = tx, merkle
                 await asyncio.sleep(0)
+        for tx_height, v in tx_heights_and_positions.items():
+            get_merkle_branch = merkles[tx_height].branch
+            for (tx_hash_bytes, tx, tx_num, tx_pos) in v:
+                tx_infos[tx_hash_bytes[::-1].hex()] = None if not tx else tx.hex(), {
+                    'block_height': tx_height,
+                    'merkle': get_merkle_branch(tx_pos),
+                    'pos': tx_pos
+                }
+        for tx_hash_bytes, tx in cached_mempool:
+            tx_infos[tx_hash_bytes[::-1].hex()] = None if not tx else tx.hex(), {'block_height': -1}
         if needed_mempool:
             for tx_hash_bytes, tx in zip(needed_mempool, await run_in_executor(
                     self._executor, self.prefix_db.mempool_tx.multi_get, [(tx_hash,) for tx_hash in needed_mempool],
                     True, False)):
+                self.tx_cache[tx_hash_bytes] = tx, None, None, -1
                 tx_infos[tx_hash_bytes[::-1].hex()] = None if not tx else tx.hex(), {'block_height': -1}
                 await asyncio.sleep(0)
-        return tx_infos
+        return {txid: tx_infos.get(txid) for txid in txids}  # match ordering of the txs in the request
 
     async def fs_block_hashes(self, height, count):
         if height + count > len(self.headers):

scribe/service.py

@@ -151,12 +151,20 @@ class BlockchainReaderService(BlockchainService):
         assert len(self.db.tx_counts) == height, f"{len(self.db.tx_counts)} != {height}"
         prev_count = self.db.tx_counts[-1]
         self.db.tx_counts.append(tx_count)
-        if self.db._cache_all_tx_hashes:
+
-            for tx_num in range(prev_count, tx_count):
+        # precache all of the txs from this block
-                tx_hash = self.db.prefix_db.tx_hash.get(tx_num).tx_hash
+        block_tx_hashes = self.db.prefix_db.block_txs.get(height).tx_hashes
+        block_txs = self.db.prefix_db.tx.multi_get(
+            [(tx_hash,) for tx_hash in block_tx_hashes], deserialize_value=False
+        )
+        for tx_pos, (tx_num, tx_hash, tx) in enumerate(zip(range(prev_count, tx_count), block_tx_hashes, block_txs)):
+            self.db.tx_cache[tx_hash] = tx, tx_num, tx_pos, height
+            if self.db._cache_all_tx_hashes:
                 self.db.total_transactions.append(tx_hash)
                 self.db.tx_num_mapping[tx_hash] = tx_count
+        if self.db._cache_all_tx_hashes:
             assert len(self.db.total_transactions) == tx_count, f"{len(self.db.total_transactions)} vs {tx_count}"
+
         header = self.db.prefix_db.header.get(height, deserialize_value=False)
         self.db.headers.append(header)
         self.db.block_hashes.append(self.env.coin.header_hash(header))
@@ -171,8 +179,11 @@ class BlockchainReaderService(BlockchainService):
         self.db.block_hashes.pop()
         if self.db._cache_all_tx_hashes:
             for _ in range(prev_count - tx_count):
-                self.db.tx_num_mapping.pop(self.db.total_transactions.pop())
+                tx_hash = self.db.tx_num_mapping.pop(self.db.total_transactions.pop())
+                if tx_hash in self.db.tx_cache:
+                    self.db.tx_cache.pop(tx_hash)
             assert len(self.db.total_transactions) == tx_count, f"{len(self.db.total_transactions)} vs {tx_count}"
+        self.db.merkle_cache.clear()
 
     def _detect_changes(self):
         try: