blockchain: parent pointer and recursive methods

lib/blockchain.py

@@ -61,6 +61,29 @@ def hash_header(header):
     return hash_encode(Hash(serialize_header(header).decode('hex')))
 
 
+blockchains = {}
+
+def read_blockchains(config):
+    blockchains[0] = Blockchain(config, 'blockchain_headers')
+    # fixme: sort
+    for x in os.listdir(config.path):
+        if x.startswith('fork_'):
+            b = Blockchain(config, x)
+            blockchains[b.checkpoint] = b
+    return blockchains
+
+def get_blockchain(header):
+    if type(header) is not dict:
+        return False
+    header_hash = hash_header(header)
+    height = header.get('block_height')
+    for b in blockchains.values():
+        if header_hash == b.get_hash(height):
+            return b
+    return False
+
+
+
 class Blockchain(util.PrintError):
 
     '''Manages blockchain headers and their verification'''
@@ -70,26 +93,28 @@ class Blockchain(util.PrintError):
         self.filename = filename
         self.catch_up = None # interface catching up
         self.is_saved = True
-        self.checkpoint = int(filename[16:]) if filename.startswith('blockchain_fork_') else 0
         self.headers = []
+        if filename == 'blockchain_headers':
+            self.parent = None
+            self.checkpoint = 0
+        elif filename.startswith('fork_'):
+            self.parent = blockchains[int(filename.split('_')[1])]
+            self.checkpoint = int(filename.split('_')[2])
+        else:
+            raise BaseException('')
         self.set_local_height()
 
-    def fork(parent, fork_point):
+    def fork(parent, checkpoint):
-        self = Blockchain(parent.config, parent.filename)
+        filename = 'fork_%d_%d'%(parent.checkpoint, checkpoint)
+        self = Blockchain(parent.config, filename)
         self.is_saved = False
-        if parent.is_saved:
+        self.parent = parent
-            self.checkpoint = fork_point
+        self.checkpoint = checkpoint
-        else:
-            if fork_point > parent.checkpoint:
-                self.headers = parent.headers[0: fork_point - parent.checkpoint]
-            else:
-                self.headers = []
         return self
 
     def height(self):
-        if self.headers:
+        local = self.local_height if self.is_saved else len(self.headers) - 1
-            return self.checkpoint + len(self.headers) - 1
+        return self.checkpoint + local
-        return self.local_height
 
     def verify_header(self, header, prev_header, bits, target):
         prev_hash = hash_header(prev_header)
@@ -139,20 +164,15 @@ class Blockchain(util.PrintError):
         self.set_local_height()
 
     def save(self):
-        import shutil
+        # recursively save parents if they have not been saved
-        self.print_error("save fork")
+        if self.parent and not self.parent.is_saved():
-        height = self.checkpoint
+            self.parent.save()
-        filename = "blockchain_fork_%d"%height
+        open(self.path(), 'w+').close()
-        new_path = os.path.join(util.get_headers_dir(self.config), filename)
-        shutil.copy(self.path(), new_path)
-        with open(new_path, 'rb+') as f:
-            f.seek((height) * 80)
-            f.truncate()
-        self.filename = filename
-        self.is_saved = True
         for h in self.headers:
             self.write_header(h)
         self.headers = []
+        self.is_saved = True
+        self.print_error("saved", self.filename)
 
     def save_header(self, header):
         height = header.get('block_height')
@@ -165,12 +185,12 @@ class Blockchain(util.PrintError):
         self.write_header(header)
 
     def write_header(self, header):
-        height = header.get('block_height')
+        delta = header.get('block_height') - self.checkpoint
         data = serialize_header(header).decode('hex')
         assert len(data) == 80
         filename = self.path()
         with open(filename, 'rb+') as f:
-            f.seek(height * 80)
+            f.seek(delta * 80)
             f.truncate()
             h = f.write(data)
         self.set_local_height()
@@ -180,25 +200,26 @@ class Blockchain(util.PrintError):
         name = self.path()
         if os.path.exists(name):
             h = os.path.getsize(name)/80 - 1
-            if self.local_height != h:
             self.local_height = h
 
     def read_header(self, height):
-        if not self.is_saved and height >= self.checkpoint:
+        if height < self.checkpoint:
-            i = height - self.checkpoint
+            return self.parent.read_header(height)
-            if i >= len(self.headers):
+        delta = height - self.checkpoint
+        if not self.is_saved:
+            if delta >= len(self.headers):
                 return None
-            header = self.headers[i]
+            header = self.headers[delta]
             assert header.get('block_height') == height
             return header
         name = self.path()
         if os.path.exists(name):
             f = open(name, 'rb')
-            f.seek(height * 80)
+            f.seek(delta * 80)
             h = f.read(80)
             f.close()
             if len(h) == 80:
-                h = deserialize_header(h, height)
+                h = deserialize_header(h, delta)
                 return h
 
     def get_hash(self, height):

lib/network.py

@@ -40,7 +40,7 @@ import util
 import bitcoin
 from bitcoin import *
 from interface import Connection, Interface
-from blockchain import Blockchain
+from blockchain import read_blockchains, get_blockchain
 from version import ELECTRUM_VERSION, PROTOCOL_VERSION
 
 DEFAULT_PORTS = {'t':'50001', 's':'50002'}
@@ -206,11 +206,7 @@ class Network(util.DaemonThread):
         util.DaemonThread.__init__(self)
         self.config = SimpleConfig(config) if type(config) == type({}) else config
         self.num_server = 10 if not self.config.get('oneserver') else 0
-        self.blockchains = { 0:Blockchain(self.config, 'blockchain_headers') }
+        self.blockchains = read_blockchains(self.config)
-        for x in os.listdir(self.config.path):
-            if x.startswith('blockchain_fork_'):
-                b = Blockchain(self.config, x)
-                self.blockchains[b.checkpoint] = b
         self.print_error("blockchains", self.blockchains.keys())
         self.blockchain_index = config.get('blockchain_index', 0)
         if self.blockchain_index not in self.blockchains.keys():
@@ -706,18 +702,8 @@ class Network(util.DaemonThread):
     def get_checkpoint(self):
         return max(self.blockchains.keys())
 
-    def get_blockchain(self, header):
-        from blockchain import hash_header
-        if type(header) is not dict:
-            return False
-        header_hash = hash_header(header)
-        height = header.get('block_height')
-        for b in self.blockchains.values():
-            if header_hash == b.get_hash(height):
-                return b
-        return False
-
     def new_interface(self, server, socket):
+        # todo: get tip first, then decide which checkpoint to use.
         self.add_recent_server(server)
         interface = Interface(server, socket)
         interface.blockchain = None
@@ -830,7 +816,7 @@ class Network(util.DaemonThread):
     def on_header(self, interface, header):
         height = header.get('block_height')
         if interface.mode == 'checkpoint':
-            b = self.get_blockchain(header)
+            b = get_blockchain(header)
             if b:
                 interface.mode = 'default'
                 interface.blockchain = b