Remove the FS cache

Really belongs with BlockProcessor now

server/block_processor.py

@@ -10,6 +10,8 @@
 
 import array
 import asyncio
+import itertools
+import os
 import struct
 import time
 from bisect import bisect_left
@@ -411,7 +413,7 @@ class BlockProcessor(server.db.DB):
         start = self.height - 1
         count = 1
         while start > 0:
-            hashes = self.fs_cache.block_hashes(start, count)
+            hashes = self.block_hashes(start, count)
             hex_hashes = [hash_to_str(hash) for hash in hashes]
             d_hex_hashes = await self.daemon.block_hex_hashes(start, count)
             n = match_pos(hex_hashes, d_hex_hashes)
@@ -428,7 +430,7 @@ class BlockProcessor(server.db.DB):
                          'height {:,d} to height {:,d}'
                          .format(count, start, start + count - 1))
 
-        return self.fs_cache.block_hashes(start, count)
+        return self.block_hashes(start, count)
 
     def clean_db(self):
         '''Clean out stale DB items.
@@ -534,7 +536,9 @@ class BlockProcessor(server.db.DB):
         if self.height > self.db_height:
             assert flush_history is None
             flush_history = self.flush_history
-            self.fs_cache.flush(self.height, self.tx_count)
+            self.fs_flush()
+            self.logger.info('FS flush took {:.1f} seconds'
+                             .format(time.time() - flush_start))
 
         with self.db.write_batch() as batch:
             # History first - fast and frees memory.  Flush state last
@@ -593,6 +597,55 @@ class BlockProcessor(server.db.DB):
         self.history = defaultdict(partial(array.array, 'I'))
         self.history_size = 0
 
+    def fs_flush(self):
+        '''Flush the things stored on the filesystem.
+        The arguments are passed for sanity check assertions only.'''
+        blocks_done = len(self.headers)
+        prior_tx_count = (self.tx_counts[self.fs_height]
+                          if self.fs_height >= 0 else 0)
+        cur_tx_count = self.tx_counts[-1] if self.tx_counts else 0
+        txs_done = cur_tx_count - prior_tx_count
+
+        assert self.fs_height + blocks_done == self.height
+        assert len(self.tx_hashes) == blocks_done
+        assert len(self.tx_counts) == self.height + 1
+        assert cur_tx_count == self.tx_count, \
+            'cur: {:,d} new: {:,d}'.format(cur_tx_count, self.tx_count)
+
+        # First the headers
+        headers = b''.join(self.headers)
+        header_len = self.coin.HEADER_LEN
+        self.headers_file.seek((self.fs_height + 1) * header_len)
+        self.headers_file.write(headers)
+        self.headers_file.flush()
+
+        # Then the tx counts
+        self.txcount_file.seek((self.fs_height + 1) * self.tx_counts.itemsize)
+        self.txcount_file.write(self.tx_counts[self.fs_height + 1:])
+        self.txcount_file.flush()
+
+        # Finally the hashes
+        hashes = memoryview(b''.join(itertools.chain(*self.tx_hashes)))
+        assert len(hashes) % 32 == 0
+        assert len(hashes) // 32 == txs_done
+        cursor = 0
+        file_pos = prior_tx_count * 32
+        while cursor < len(hashes):
+            file_num, offset = divmod(file_pos, self.tx_hash_file_size)
+            size = min(len(hashes) - cursor, self.tx_hash_file_size - offset)
+            filename = 'hashes{:04d}'.format(file_num)
+            with self.open_file(filename, create=True) as f:
+                f.seek(offset)
+                f.write(hashes[cursor:cursor + size])
+            cursor += size
+            file_pos += size
+
+        os.sync()
+
+        self.tx_hashes = []
+        self.headers = []
+        self.fs_height += blocks_done
+
     def backup_history(self, batch, hash168s):
         self.logger.info('backing up history to height {:,d}  tx_count {:,d}'
                          .format(self.height, self.tx_count))
@@ -662,9 +715,18 @@ class BlockProcessor(server.db.DB):
         '''Read undo information from a file for the current height.'''
         return self.db.get(self.undo_key(height))
 
+    def fs_advance_block(self, header, tx_hashes, txs):
+        '''Update unflushed FS state for a new block.'''
+        prior_tx_count = self.tx_counts[-1] if self.tx_counts else 0
+
+        # Cache the new header, tx hashes and cumulative tx count
+        self.headers.append(header)
+        self.tx_hashes.append(tx_hashes)
+        self.tx_counts.append(prior_tx_count + len(txs))
+
     def advance_block(self, block, update_touched):
-        # We must update the fs_cache before calling advance_txs() as
-        # the UTXO cache uses the fs_cache via get_tx_hash() to
+        # We must update the FS cache before calling advance_txs() as
+        # the UTXO cache uses the FS cache via get_tx_hash() to
         # resolve compressed key collisions
         header, tx_hashes, txs = self.coin.read_block(block)
         prev_hash, header_hash = self.coin.header_hashes(header)
@@ -672,7 +734,7 @@ class BlockProcessor(server.db.DB):
             raise ChainReorg
 
         touched = set()
-        self.fs_cache.advance_block(header, tx_hashes, txs)
+        self.fs_advance_block(header, tx_hashes, txs)
         self.tip = header_hash
         self.height += 1
         undo_info = self.advance_txs(tx_hashes, txs, touched)
@@ -733,6 +795,16 @@ class BlockProcessor(server.db.DB):
 
         return undo_info
 
+    def fs_backup_block(self):
+        '''Revert a block.'''
+        assert not self.headers
+        assert not self.tx_hashes
+        assert self.fs_height >= 0
+        # Just update in-memory.  It doesn't matter if disk files are
+        # too long, they will be overwritten when advancing.
+        self.fs_height -= 1
+        self.tx_counts.pop()
+
     def backup_blocks(self, blocks):
         '''Backup the blocks and flush.
 
@@ -752,7 +824,7 @@ class BlockProcessor(server.db.DB):
                                          hash_to_str(self.tip), self.height))
 
             self.backup_txs(tx_hashes, txs, touched)
-            self.fs_cache.backup_block()
+            self.fs_backup_block()
             self.tip = prev_hash
             self.height -= 1
 

server/cache.py

@@ -12,14 +12,10 @@ Once synced flushes are performed after processing each block.
 '''
 
 
-import array
-import itertools
-import os
 import struct
-from bisect import bisect_right
 
-from lib.util import chunks, LoggedClass
-from lib.hash import double_sha256, hash_to_str
+from lib.util import LoggedClass
+from lib.hash import hash_to_str
 
 
 # History can hold approx. 65536 * HIST_ENTRIES_PER_KEY entries
@@ -259,155 +255,3 @@ class UTXOCache(LoggedClass):
                          .format(new_utxos, self.db_deletes,
                                  hcolls, ucolls))
         self.cache_spends = self.db_deletes = 0
-
-
-class FSCache(LoggedClass):
-
-    def __init__(self, coin, height, tx_count):
-        super().__init__()
-
-        self.coin = coin
-        self.tx_hash_file_size = 16 * 1024 * 1024
-        assert self.tx_hash_file_size % 32 == 0
-
-        # On-disk values, updated by a flush
-        self.height = height
-
-        # Unflushed items
-        self.headers = []
-        self.tx_hashes = []
-
-        is_new = height == -1
-        self.headers_file = self.open_file('headers', is_new)
-        self.txcount_file = self.open_file('txcount', is_new)
-
-        # tx_counts[N] has the cumulative number of txs at the end of
-        # height N.  So tx_counts[0] is 1 - the genesis coinbase
-        self.tx_counts = array.array('I')
-        self.txcount_file.seek(0)
-        self.tx_counts.fromfile(self.txcount_file, self.height + 1)
-        if self.tx_counts:
-            assert tx_count == self.tx_counts[-1]
-        else:
-            assert tx_count == 0
-
-    def open_file(self, filename, create=False):
-        '''Open the file name.  Return its handle.'''
-        try:
-            return open(filename, 'rb+')
-        except FileNotFoundError:
-            if create:
-                return open(filename, 'wb+')
-            raise
-
-    def advance_block(self, header, tx_hashes, txs):
-        '''Update the FS cache for a new block.'''
-        prior_tx_count = self.tx_counts[-1] if self.tx_counts else 0
-
-        # Cache the new header, tx hashes and cumulative tx count
-        self.headers.append(header)
-        self.tx_hashes.append(tx_hashes)
-        self.tx_counts.append(prior_tx_count + len(txs))
-
-    def backup_block(self):
-        '''Revert a block.'''
-        assert not self.headers
-        assert not self.tx_hashes
-        assert self.height >= 0
-        # Just update in-memory.  It doesn't matter if disk files are
-        # too long, they will be overwritten when advancing.
-        self.height -= 1
-        self.tx_counts.pop()
-
-    def flush(self, new_height, new_tx_count):
-        '''Flush the things stored on the filesystem.
-        The arguments are passed for sanity check assertions only.'''
-        self.logger.info('flushing to file system')
-
-        blocks_done = len(self.headers)
-        prior_tx_count = self.tx_counts[self.height] if self.height >= 0 else 0
-        cur_tx_count = self.tx_counts[-1] if self.tx_counts else 0
-        txs_done = cur_tx_count - prior_tx_count
-
-        assert self.height + blocks_done == new_height
-        assert len(self.tx_hashes) == blocks_done
-        assert len(self.tx_counts) == new_height + 1
-        assert cur_tx_count == new_tx_count, \
-            'cur: {:,d} new: {:,d}'.format(cur_tx_count, new_tx_count)
-
-        # First the headers
-        headers = b''.join(self.headers)
-        header_len = self.coin.HEADER_LEN
-        self.headers_file.seek((self.height + 1) * header_len)
-        self.headers_file.write(headers)
-        self.headers_file.flush()
-
-        # Then the tx counts
-        self.txcount_file.seek((self.height + 1) * self.tx_counts.itemsize)
-        self.txcount_file.write(self.tx_counts[self.height + 1:])
-        self.txcount_file.flush()
-
-        # Finally the hashes
-        hashes = memoryview(b''.join(itertools.chain(*self.tx_hashes)))
-        assert len(hashes) % 32 == 0
-        assert len(hashes) // 32 == txs_done
-        cursor = 0
-        file_pos = prior_tx_count * 32
-        while cursor < len(hashes):
-            file_num, offset = divmod(file_pos, self.tx_hash_file_size)
-            size = min(len(hashes) - cursor, self.tx_hash_file_size - offset)
-            filename = 'hashes{:04d}'.format(file_num)
-            with self.open_file(filename, create=True) as f:
-                f.seek(offset)
-                f.write(hashes[cursor:cursor + size])
-            cursor += size
-            file_pos += size
-
-        os.sync()
-
-        self.tx_hashes = []
-        self.headers = []
-        self.height += blocks_done
-
-    def read_headers(self, start, count):
-        result = b''
-
-        # Read some from disk
-        disk_count = min(count, self.height + 1 - start)
-        if disk_count > 0:
-            header_len = self.coin.HEADER_LEN
-            assert start >= 0
-            self.headers_file.seek(start * header_len)
-            result = self.headers_file.read(disk_count * header_len)
-            count -= disk_count
-            start += disk_count
-
-        # The rest from memory
-        start -= self.height + 1
-        assert count >= 0 and start + count <= len(self.headers)
-        result += b''.join(self.headers[start: start + count])
-
-        return result
-
-    def get_tx_hash(self, tx_num):
-        '''Returns the tx_hash and height of a tx number.'''
-        height = bisect_right(self.tx_counts, tx_num)
-
-        # Is this on disk or unflushed?
-        if height > self.height:
-            tx_hashes = self.tx_hashes[height - (self.height + 1)]
-            tx_hash = tx_hashes[tx_num - self.tx_counts[height - 1]]
-        else:
-            file_pos = tx_num * 32
-            file_num, offset = divmod(file_pos, self.tx_hash_file_size)
-            filename = 'hashes{:04d}'.format(file_num)
-            with self.open_file(filename) as f:
-                f.seek(offset)
-                tx_hash = f.read(32)
-
-        return tx_hash, height
-
-    def block_hashes(self, height, count):
-        headers = self.read_headers(height, count)
-        hlen = self.coin.HEADER_LEN
-        return [double_sha256(header) for header in chunks(headers, hlen)]

server/db.py

@@ -12,10 +12,11 @@ import array
 import ast
 import os
 import struct
+from bisect import bisect_right
 from collections import namedtuple
 
-from server.cache import FSCache, NO_CACHE_ENTRY
-from lib.util import LoggedClass
+from lib.util import chunks, LoggedClass
+from lib.hash import double_sha256
 from server.storage import open_db
 
 UTXO = namedtuple("UTXO", "tx_num tx_pos tx_hash height value")
@@ -54,10 +55,29 @@ class DB(LoggedClass):
         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
+        # -- FS related members --
+        self.tx_hash_file_size = 16 * 1024 * 1024
+
+        # On-disk height updated by a flush
+        self.fs_height = self.height
+
+        # Unflushed items
+        self.headers = []
+        self.tx_hashes = []
+
+        create = self.height == -1
+        self.headers_file = self.open_file('headers', create)
+        self.txcount_file = self.open_file('txcount', create)
+
+        # tx_counts[N] has the cumulative number of txs at the end of
+        # height N.  So tx_counts[0] is 1 - the genesis coinbase
+        self.tx_counts = array.array('I')
+        self.txcount_file.seek(0)
+        self.tx_counts.fromfile(self.txcount_file, self.height + 1)
+        if self.tx_counts:
+            assert self.tx_count == self.tx_counts[-1]
+        else:
+            assert self.tx_count == 0
 
     def init_state_from_db(self):
         if self.db.is_new:
@@ -83,6 +103,59 @@ class DB(LoggedClass):
             self.wall_time = state['wall_time']
             self.first_sync = state.get('first_sync', True)
 
+    def open_file(self, filename, create=False):
+        '''Open the file name.  Return its handle.'''
+        try:
+            return open(filename, 'rb+')
+        except FileNotFoundError:
+            if create:
+                return open(filename, 'wb+')
+            raise
+
+    def read_headers(self, start, count):
+        result = b''
+
+        # Read some from disk
+        disk_count = min(count, self.fs_height + 1 - start)
+        if disk_count > 0:
+            header_len = self.coin.HEADER_LEN
+            assert start >= 0
+            self.headers_file.seek(start * header_len)
+            result = self.headers_file.read(disk_count * header_len)
+            count -= disk_count
+            start += disk_count
+
+        # The rest from memory
+        start -= self.fs_height + 1
+        assert count >= 0 and start + count <= len(self.headers)
+        result += b''.join(self.headers[start: start + count])
+
+        return result
+
+    def get_tx_hash(self, tx_num):
+        '''Returns the tx_hash and height of a tx number.'''
+        height = bisect_right(self.tx_counts, tx_num)
+
+        # Is this on disk or unflushed?
+        if height > self.fs_height:
+            tx_hashes = self.tx_hashes[height - (self.fs_height + 1)]
+            tx_hash = tx_hashes[tx_num - self.tx_counts[height - 1]]
+        else:
+            file_pos = tx_num * 32
+            file_num, offset = divmod(file_pos, self.tx_hash_file_size)
+            filename = 'hashes{:04d}'.format(file_num)
+            with self.open_file(filename) as f:
+                f.seek(offset)
+                tx_hash = f.read(32)
+
+        return tx_hash, height
+
+    def block_hashes(self, height, count):
+        headers = self.read_headers(height, count)
+        # FIXME: move to coins.py
+        hlen = self.coin.HEADER_LEN
+        return [double_sha256(header) for header in chunks(headers, hlen)]
+
     @staticmethod
     def _resolve_limit(limit):
         if limit is None:
@@ -142,9 +215,7 @@ class DB(LoggedClass):
         hash168 = None
         if 0 <= index <= 65535:
             idx_packed = struct.pack('<H', index)
-            hash168 = self.hash168(tx_hash, idx_packed, False)
-            if hash168 == NO_CACHE_ENTRY:
-                hash168 = None
+            hash168 = self.hash168(tx_hash, idx_packed)
         return hash168
 
     def hash168(self, tx_hash, idx_packed):