From c0a112f8ea3a9d5bc790fdc149f90b91b62dcfe3 Mon Sep 17 00:00:00 2001
From: Neil Booth <kyuupichan@gmail.com>
Date: Tue, 8 Nov 2016 07:32:55 +0900
Subject: [PATCH] Split out part of block processor into db.py

The part that doesn't actually do any block processing...
---
 server/block_processor.py | 124 ++-------------------------------
 server/cache.py           |   8 +--
 server/db.py              | 142 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 151 insertions(+), 123 deletions(-)
 create mode 100644 server/db.py

diff --git a/server/block_processor.py b/server/block_processor.py
index 6116924..1412cbc 100644
--- a/server/block_processor.py
+++ b/server/block_processor.py
@@ -22,6 +22,7 @@ from server.daemon import DaemonError
 from lib.hash import hash_to_str
 from lib.tx import Deserializer
 from lib.util import chunks, LoggedClass
+import server.db
 from server.storage import open_db
 
 
@@ -33,9 +34,6 @@ def formatted_time(t):
         t // 86400, (t % 86400) // 3600, (t % 3600) // 60, t % 60)
 
 
-UTXO = namedtuple("UTXO", "tx_num tx_pos tx_hash height value")
-
-
 class ChainError(Exception):
     pass
 
@@ -283,7 +281,7 @@ class MemPool(LoggedClass):
         return value
 
 
-class BlockProcessor(LoggedClass):
+class BlockProcessor(server.db.DB):
     '''Process blocks and update the DB state to match.
 
     Employ a prefetcher to prefetch blocks in batches for processing.
@@ -292,9 +290,8 @@ class BlockProcessor(LoggedClass):
 
     def __init__(self, env, daemon, on_update=None):
         '''on_update is awaitable, and called only when caught up with the
-        daemon and a new block arrives or the mempool is updated.
-        '''
-        super().__init__()
+        daemon and a new block arrives or the mempool is updated.'''
+        super().__init__(env.coin, env.db_engine)
 
         self.daemon = daemon
         self.on_update = on_update
@@ -305,39 +302,16 @@ class BlockProcessor(LoggedClass):
         self.utxo_MB = env.utxo_MB
         self.hist_MB = env.hist_MB
         self.next_cache_check = 0
-        self.coin = env.coin
         self.reorg_limit = env.reorg_limit
 
-        # Open DB and metadata files.  Record some of its state.
-        db_name = '{}-{}'.format(self.coin.NAME, self.coin.NET)
-        self.db = open_db(db_name, env.db_engine)
-        if self.db.is_new:
-            self.logger.info('created new {} database {}'
-                             .format(env.db_engine, db_name))
-        else:
-            self.logger.info('successfully opened {} database {}'
-                             .format(env.db_engine, db_name))
-
-        self.init_state()
-        self.tx_count = self.db_tx_count
-        self.height = self.db_height
-        self.tip = self.db_tip
-
-        # Caches to be flushed later.  Headers and tx_hashes have one
-        # entry per block
+        # Headers and tx_hashes have one entry per block
         self.history = defaultdict(partial(array.array, 'I'))
         self.history_size = 0
-        self.utxo_cache = UTXOCache(self, self.db, self.coin)
-        self.fs_cache = FSCache(self.coin, self.height, self.tx_count)
         self.prefetcher = Prefetcher(daemon, self.height)
 
         self.last_flush = time.time()
         self.last_flush_tx_count = self.tx_count
 
-        # Redirected member funcs
-        self.get_tx_hash = self.fs_cache.get_tx_hash
-        self.read_headers = self.fs_cache.read_headers
-
         # Log state
         self.logger.info('{}/{} height: {:,d} tx count: {:,d} '
                          'flush count: {:,d} utxo flush count: {:,d} '
@@ -451,30 +425,6 @@ class BlockProcessor(LoggedClass):
 
         return self.fs_cache.block_hashes(start, count)
 
-    def init_state(self):
-        if self.db.is_new:
-            self.db_height = -1
-            self.db_tx_count = 0
-            self.db_tip = b'\0' * 32
-            self.flush_count = 0
-            self.utxo_flush_count = 0
-            self.wall_time = 0
-            self.first_sync = True
-        else:
-            state = self.db.get(b'state')
-            state = ast.literal_eval(state.decode())
-            if state['genesis'] != self.coin.GENESIS_HASH:
-                raise ChainError('DB genesis hash {} does not match coin {}'
-                                 .format(state['genesis_hash'],
-                                         self.coin.GENESIS_HASH))
-            self.db_height = state['height']
-            self.db_tx_count = state['tx_count']
-            self.db_tip = state['tip']
-            self.flush_count = state['flush_count']
-            self.utxo_flush_count = state['utxo_flush_count']
-            self.wall_time = state['wall_time']
-            self.first_sync = state.get('first_sync', True)
-
     def clean_db(self):
         '''Clean out stale DB items.
 
@@ -839,13 +789,6 @@ class BlockProcessor(LoggedClass):
         assert n == 0
         self.tx_count -= len(txs)
 
-    @staticmethod
-    def resolve_limit(limit):
-        if limit is None:
-            return -1
-        assert isinstance(limit, int) and limit >= 0
-        return limit
-
     def mempool_transactions(self, hash168):
         '''Generate (hex_hash, tx_fee, unconfirmed) tuples for mempool
         entries for the hash168.
@@ -860,60 +803,3 @@ class BlockProcessor(LoggedClass):
         Can be positive or negative.
         '''
         return self.mempool.value(hash168)
-
-    def get_history(self, hash168, limit=1000):
-        '''Generator that returns an unpruned, sorted list of (tx_hash,
-        height) tuples of confirmed transactions that touched the address,
-        earliest in the blockchain first.  Includes both spending and
-        receiving transactions.  By default yields at most 1000 entries.
-        Set limit to None to get them all.
-        '''
-        limit = self.resolve_limit(limit)
-        prefix = b'H' + hash168
-        for key, hist in self.db.iterator(prefix=prefix):
-            a = array.array('I')
-            a.frombytes(hist)
-            for tx_num in a:
-                if limit == 0:
-                    return
-                yield self.get_tx_hash(tx_num)
-                limit -= 1
-
-    def get_balance(self, hash168):
-        '''Returns the confirmed balance of an address.'''
-        return sum(utxo.value for utxo in self.get_utxos(hash168, limit=None))
-
-    def get_utxos(self, hash168, limit=1000):
-        '''Generator that yields all UTXOs for an address sorted in no
-        particular order.  By default yields at most 1000 entries.
-        Set limit to None to get them all.
-        '''
-        limit = self.resolve_limit(limit)
-        unpack = struct.unpack
-        prefix = b'u' + hash168
-        for k, v in self.db.iterator(prefix=prefix):
-            (tx_pos,) = unpack('<H', k[-2:])
-
-            for n in range(0, len(v), 12):
-                if limit == 0:
-                    return
-                (tx_num,) = unpack('<I', v[n:n + 4])
-                (value,) = unpack('<Q', v[n + 4:n + 12])
-                tx_hash, height = self.get_tx_hash(tx_num)
-                yield UTXO(tx_num, tx_pos, tx_hash, height, value)
-                limit -= 1
-
-    def get_utxos_sorted(self, hash168):
-        '''Returns all the UTXOs for an address sorted by height and
-        position in the block.'''
-        return sorted(self.get_utxos(hash168, limit=None))
-
-    def get_utxo_hash168(self, tx_hash, index):
-        '''Returns the hash168 for a UTXO.'''
-        hash168 = None
-        if 0 <= index <= 65535:
-            idx_packed = struct.pack('<H', index)
-            hash168 = self.utxo_cache.hash168(tx_hash, idx_packed, False)
-            if hash168 == NO_CACHE_ENTRY:
-                hash168 = None
-        return hash168
diff --git a/server/cache.py b/server/cache.py
index 5f27662..f06eb49 100644
--- a/server/cache.py
+++ b/server/cache.py
@@ -83,9 +83,9 @@ class UTXOCache(LoggedClass):
 
     '''
 
-    def __init__(self, parent, db, coin):
+    def __init__(self, get_tx_hash, db, coin):
         super().__init__()
-        self.parent = parent
+        self.get_tx_hash = get_tx_hash
         self.coin = coin
         self.cache = {}
         self.put = self.cache.__setitem__
@@ -137,7 +137,7 @@ class UTXOCache(LoggedClass):
         assert len(data) % 12 == 0
         for n in range(0, len(data), 12):
             (tx_num, ) = struct.unpack('<I', data[n:n+4])
-            this_tx_hash, height = self.parent.get_tx_hash(tx_num)
+            this_tx_hash, height = self.get_tx_hash(tx_num)
             if tx_hash == this_tx_hash:
                 result = hash168 + data[n:n+12]
                 if delete:
@@ -185,7 +185,7 @@ class UTXOCache(LoggedClass):
         # Resolve the compressed key collision using the TX number
         for n in range(0, len(data), 25):
             (tx_num, ) = struct.unpack('<I', data[n+21:n+25])
-            my_hash, height = self.parent.get_tx_hash(tx_num)
+            my_hash, height = self.get_tx_hash(tx_num)
             if my_hash == tx_hash:
                 if delete:
                     self.cache_write(key, data[:n] + data[n+25:])
diff --git a/server/db.py b/server/db.py
new file mode 100644
index 0000000..f253213
--- /dev/null
+++ b/server/db.py
@@ -0,0 +1,142 @@
+# Copyright (c) 2016, Neil Booth
+#
+# All rights reserved.
+#
+# See the file "LICENCE" for information about the copyright
+# and warranty status of this software.
+
+'''Interface to the blockchain database.'''
+
+import array
+import ast
+import struct
+from collections import namedtuple
+
+from server.cache import FSCache, UTXOCache, NO_CACHE_ENTRY
+from lib.util import LoggedClass
+from server.storage import open_db
+
+UTXO = namedtuple("UTXO", "tx_num tx_pos tx_hash height value")
+
+
+class DB(LoggedClass):
+    '''Simple wrapper of the backend database for querying.
+
+    Performs no DB update, though the DB will be cleaned on opening if
+    it was shutdown uncleanly.
+    '''
+
+    def __init__(self, coin, db_engine):
+        super().__init__()
+        self.coin = coin
+
+        # Open DB and metadata files.  Record some of its state.
+        db_name = '{}-{}'.format(coin.NAME, coin.NET)
+        self.db = open_db(db_name, db_engine)
+        if self.db.is_new:
+            self.logger.info('created new {} database {}'
+                             .format(db_engine, db_name))
+        else:
+            self.logger.info('successfully opened {} database {}'
+                             .format(db_engine, db_name))
+
+        self.init_state_from_db()
+        self.tx_count = self.db_tx_count
+        self.height = self.db_height
+        self.tip = self.db_tip
+
+        # Cache wrapping the filesystem and redirected functions
+        self.fs_cache = FSCache(self.coin, self.height, self.tx_count)
+        self.get_tx_hash = self.fs_cache.get_tx_hash
+        self.read_headers = self.fs_cache.read_headers
+
+        # UTXO cache
+        self.utxo_cache = UTXOCache(self.get_tx_hash, self.db, self.coin)
+
+    def init_state_from_db(self):
+        if self.db.is_new:
+            self.db_height = -1
+            self.db_tx_count = 0
+            self.db_tip = b'\0' * 32
+            self.flush_count = 0
+            self.utxo_flush_count = 0
+            self.wall_time = 0
+            self.first_sync = True
+        else:
+            state = self.db.get(b'state')
+            state = ast.literal_eval(state.decode())
+            if state['genesis'] != self.coin.GENESIS_HASH:
+                raise ChainError('DB genesis hash {} does not match coin {}'
+                                 .format(state['genesis_hash'],
+                                         self.coin.GENESIS_HASH))
+            self.db_height = state['height']
+            self.db_tx_count = state['tx_count']
+            self.db_tip = state['tip']
+            self.flush_count = state['flush_count']
+            self.utxo_flush_count = state['utxo_flush_count']
+            self.wall_time = state['wall_time']
+            self.first_sync = state.get('first_sync', True)
+
+    @staticmethod
+    def _resolve_limit(limit):
+        if limit is None:
+            return -1
+        assert isinstance(limit, int) and limit >= 0
+        return limit
+
+    def get_history(self, hash168, limit=1000):
+        '''Generator that returns an unpruned, sorted list of (tx_hash,
+        height) tuples of confirmed transactions that touched the address,
+        earliest in the blockchain first.  Includes both spending and
+        receiving transactions.  By default yields at most 1000 entries.
+        Set limit to None to get them all.
+        '''
+        limit = self._resolve_limit(limit)
+        prefix = b'H' + hash168
+        for key, hist in self.db.iterator(prefix=prefix):
+            a = array.array('I')
+            a.frombytes(hist)
+            for tx_num in a:
+                if limit == 0:
+                    return
+                yield self.get_tx_hash(tx_num)
+                limit -= 1
+
+    def get_balance(self, hash168):
+        '''Returns the confirmed balance of an address.'''
+        return sum(utxo.value for utxo in self.get_utxos(hash168, limit=None))
+
+    def get_utxos(self, hash168, limit=1000):
+        '''Generator that yields all UTXOs for an address sorted in no
+        particular order.  By default yields at most 1000 entries.
+        Set limit to None to get them all.
+        '''
+        limit = self._resolve_limit(limit)
+        unpack = struct.unpack
+        prefix = b'u' + hash168
+        for k, v in self.db.iterator(prefix=prefix):
+            (tx_pos,) = unpack('<H', k[-2:])
+
+            for n in range(0, len(v), 12):
+                if limit == 0:
+                    return
+                (tx_num,) = unpack('<I', v[n:n + 4])
+                (value,) = unpack('<Q', v[n + 4:n + 12])
+                tx_hash, height = self.get_tx_hash(tx_num)
+                yield UTXO(tx_num, tx_pos, tx_hash, height, value)
+                limit -= 1
+
+    def get_utxos_sorted(self, hash168):
+        '''Returns all the UTXOs for an address sorted by height and
+        position in the block.'''
+        return sorted(self.get_utxos(hash168, limit=None))
+
+    def get_utxo_hash168(self, tx_hash, index):
+        '''Returns the hash168 for a UTXO.'''
+        hash168 = None
+        if 0 <= index <= 65535:
+            idx_packed = struct.pack('<H', index)
+            hash168 = self.utxo_cache.hash168(tx_hash, idx_packed, False)
+            if hash168 == NO_CACHE_ENTRY:
+                hash168 = None
+        return hash168