Create MemPoolAPI and use it

electrumx/server/controller.py

@@ -14,7 +14,7 @@ from electrumx.lib.server_base import ServerBase
 from electrumx.lib.util import version_string
 from electrumx.server.chain_state import ChainState
 from electrumx.server.db import DB
-from electrumx.server.mempool import MemPool
+from electrumx.server.mempool import MemPool, MemPoolAPI
 from electrumx.server.session import SessionManager
 
 
@@ -97,8 +97,18 @@ class Controller(ServerBase):
         db = DB(env)
         BlockProcessor = env.coin.BLOCK_PROCESSOR
         bp = BlockProcessor(env, db, daemon, notifications)
-        mempool = MemPool(env.coin, daemon, notifications, db.lookup_utxos)
         chain_state = ChainState(env, db, daemon, bp)
+
+        # Set ourselves up to implement the MemPoolAPI
+        self.height = daemon.height
+        self.cached_height = daemon.cached_height
+        self.mempool_hashes = daemon.mempool_hashes
+        self.raw_transactions = daemon.getrawtransactions
+        self.lookup_utxos = db.lookup_utxos
+        self.on_mempool = notifications.on_mempool
+        MemPoolAPI.register(Controller)
+        mempool = MemPool(env.coin, self)
+
         session_mgr = SessionManager(env, chain_state, mempool,
                                      notifications, shutdown_event)
 

electrumx/server/mempool.py

@@ -10,6 +10,7 @@
 import asyncio
 import itertools
 import time
+from abc import ABC, abstractmethod
 from collections import defaultdict
 
 import attr
@@ -30,9 +31,53 @@ class MemPoolTx(object):
     size = attr.ib()
 
 
+class MemPoolAPI(ABC):
+    '''A concrete instance of this class is passed to the MemPool object
+    and used by it to query DB and blockchain state.'''
+
+    @abstractmethod
+    async def height(self):
+        '''Query bitcoind for its height.'''
+
+    @abstractmethod
+    def cached_height(self):
+        '''Return the height of bitcoind the last time it was queried,
+        for any reason, without actually querying it.
+        '''
+
+    @abstractmethod
+    async def mempool_hashes(self):
+        '''Query bitcoind for the hashes of all transactions in its
+        mempool, returned as a list.'''
+
+    @abstractmethod
+    async def raw_transactions(self, hex_hashes):
+        '''Query bitcoind for the serialized raw transactions with the given
+        hashes.  Missing transactions are returned as None.
+
+        hex_hashes is an iterable of hexadecimal hash strings.'''
+
+    @abstractmethod
+    async def lookup_utxos(self, prevouts):
+        '''Return a list of (hashX, value) pairs each prevout if unspent,
+        otherwise return None if spent or not found.
+
+        prevouts - an iterable of (hash, index) pairs
+        '''
+
+    @abstractmethod
+    async def on_mempool(self, touched, height):
+        '''Called each time the mempool is synchronized.  touched is a set of
+        hashXs touched since the previous call.  height is the
+        daemon's height at the time the mempool was obtained.'''
+
+
 class MemPool(object):
     '''Representation of the daemon's mempool.
 
+        coin - a coin class from coins.py
+        api - an object implementing MemPoolAPI
+
     Updated regularly in caught-up state.  Goal is to enable efficient
     response to the calls in the external interface.  To that end we
     maintain the following maps:
@@ -41,12 +86,11 @@ class MemPool(object):
        hashXs: hashX   -> set of all hashes of txs touching the hashX
     '''
 
-    def __init__(self, coin, daemon, notifications, lookup_utxos):
-        self.logger = class_logger(__name__, self.__class__.__name__)
+    def __init__(self, coin, api):
+        assert isinstance(api, MemPoolAPI)
         self.coin = coin
-        self.lookup_utxos = lookup_utxos
-        self.daemon = daemon
-        self.notifications = notifications
+        self.api = api
+        self.logger = class_logger(__name__, self.__class__.__name__)
         self.txs = {}
         self.hashXs = defaultdict(set)  # None can be a key
         self.cached_compact_histogram = []
@@ -132,14 +176,14 @@ class MemPool(object):
         sleep = 5
         histogram_refresh = self.coin.MEMPOOL_HISTOGRAM_REFRESH_SECS // sleep
         for loop_count in itertools.count():
-            height = self.daemon.cached_height()
-            hex_hashes = await self.daemon.mempool_hashes()
-            if height != await self.daemon.height():
+            height = self.api.cached_height()
+            hex_hashes = await self.api.mempool_hashes()
+            if height != await self.api.height():
                 continue
             hashes = set(hex_str_to_hash(hh) for hh in hex_hashes)
             touched = await self._process_mempool(hashes)
             synchronized_event.set()
-            await self.notifications.on_mempool(touched, height)
+            await self.api.on_mempool(touched, height)
             # Thread mempool histogram refreshes - they can be expensive
             if loop_count % histogram_refresh == 0:
                 await run_in_thread(self._update_histogram)
@@ -193,7 +237,7 @@ class MemPool(object):
     async def _fetch_and_accept(self, hashes, all_hashes, touched):
         '''Fetch a list of mempool transactions.'''
         hex_hashes_iter = (hash_to_hex_str(hash) for hash in hashes)
-        raw_txs = await self.daemon.getrawtransactions(hex_hashes_iter)
+        raw_txs = await self.api.raw_transactions(hex_hashes_iter)
 
         def deserialize_txs():    # This function is pure
             to_hashX = self.coin.hashX_from_script
@@ -225,7 +269,7 @@ class MemPool(object):
         prevouts = tuple(prevout for tx in tx_map.values()
                          for prevout in tx.prevouts
                          if prevout[0] not in all_hashes)
-        utxos = await self.lookup_utxos(prevouts)
+        utxos = await self.api.lookup_utxos(prevouts)
         utxo_map = {prevout: utxo for prevout, utxo in zip(prevouts, utxos)}
 
         return self._accept_transactions(tx_map, utxo_map, touched)
@@ -271,7 +315,8 @@ class MemPool(object):
         '''Return a set of (prev_hash, prev_idx) pairs from mempool
         transactions that touch hashX.
 
-        None, some or all of these may be spends of the hashX.
+        None, some or all of these may be spends of the hashX, but all
+        actual spends of it (in the DB or mempool) will be included.
         '''
         result = set()
         for tx_hash in self.hashXs.get(hashX, ()):