Merge pull request #13 from iotaledger/release/1.1.0

PyOTA-PoW v1.1.0

init.sh

@@ -13,6 +13,31 @@ rm -f pow/libccurl.so
 # Get current working directory
 WD=$(pwd)
 
+# By default, ccurl lib compiles with debug symbols, that we don't necessarly
+# want to see when using the interface. Remove them before building.
+
+# Definition of a DEBUG symbol
+pattern='#ifndef DEBUG'
+
+# Find files that define DEBUG symbols in ccurl repo
+result=$(grep -rnw 'ccurl_repo/' -e "$pattern" -l)
+
+# Result is not empty
+if [ -n "$result" ]; then
+    # Transform cmd output to array
+    readarray -t files <<<$result
+
+    # Go thorugh the files and delete line with pattern + 2 follwing lines
+    # A definition in c looks like this:
+    #   #ifndef DEBUG
+    #   define DEBUG
+    #   endif
+    for i in "${files[@]}"; do
+        echo "Removing DEBUG symbols from $i"
+        sed -i -e "/$pattern/,+2d" $i
+    done
+fi
+
 # Bulding using cmake
 echo "Building ccurl library with cmake..."
 cd ccurl_repo/ccurl && mkdir -p build && cd build && cmake .. && cmake --build .

pow/ccurl_interface.py

@@ -7,6 +7,8 @@
 import math
 import time
 from iota.exceptions import with_context
+import logging
+from sys import stderr
 
 from pkg_resources import resource_filename
 libccurl_path = resource_filename("pow","libccurl.so")
@@ -24,6 +26,10 @@
 _libccurl.ccurl_digest_transaction.restype = POINTER(c_char)
 _libccurl.ccurl_digest_transaction.argtypes = [c_char_p]
 
+# Create a logger
+logger = logging.getLogger(__name__)
+logging.basicConfig(stream=stderr, level=logging.INFO)
+
 def check_tx_trytes_length(trytes):
     """
     Checks if trytes are exactly one transaction in length.
@@ -66,7 +72,7 @@ def get_powed_tx_trytes( trytes, mwm ):
 def get_hash_trytes(trytes):
     """
     Calls `ccurl_digest_transaction` function from ccurl
-    library to calculate `rtansaction hash`. Returns the
+    library to calculate `transaction hash`. Returns the
     81 trytes long hash in unicode string format.
     """
     # Make sure we supply the right size of tx trytes to ccurl
@@ -111,41 +117,77 @@ def attach_to_tangle(bundle_trytes, # Iterable[TryteString]
     # Construct bundle object
     bundle = Bundle.from_tryte_strings(bundle_trytes)
 
-    # reversed, beause pyota bundles look like [...tx2,tx1,tx0]
-    # and we need the tail tx first (tx0)
+    # Used for checking hash
+    trailing_zeros = [0] * mwm
+
+    # reversed, beause pyota bundles look like [tx0,tx1,...]
+    # and we need the head (last) tx first
     for txn in reversed(bundle.transactions):
-        txn.attachment_timestamp = get_current_ms()
-        txn.attachment_timestamp_upper_bound = (math.pow(3,27) - 1) // 2
-
-        if (not previoustx): # this is the tail transaction
-            if txn.current_index == txn.last_index:
-                txn.branch_transaction_hash = branch_transaction_hash
-                txn.trunk_transaction_hash = trunk_transaction_hash
+        # Ccurl lib sometimes needs a kick to return the correct powed trytes.
+        # We can check the correctness by examining trailing zeros of the
+        # transaction hash. If that fails, we try calculating the pow again.
+        # Use `max_iter` to prevent infinite loop. Calculation error appears
+        # rarely, and usually the second try yields correct result. If we reach
+        # `max_iter`, we raise a ValueError.
+        max_iter = 5
+        i = 0
+
+        # If calculation is successful, we break out from the while loop.
+        while i != max_iter:
+            # Fill timestamps
+            txn.attachment_timestamp = get_current_ms()
+            txn.attachment_timestamp_upper_bound = (math.pow(3,27) - 1) // 2
+
+            # Determine correct trunk and branch transaction
+            if (not previoustx): # this is the head transaction
+                if txn.current_index == txn.last_index:
+                    txn.branch_transaction_hash = branch_transaction_hash
+                    txn.trunk_transaction_hash = trunk_transaction_hash
+                else:
+                    raise ValueError('Head transaction is inconsistent in bundle')
+
+            else: # It is not the head transaction
+                txn.branch_transaction_hash = trunk_transaction_hash
+                txn.trunk_transaction_hash = previoustx # the previous transaction
+
+            # Let's do the pow locally
+            txn_string = txn.as_tryte_string().__str__()
+            # returns a python unicode string
+            powed_txn_string = get_powed_tx_trytes(txn_string, mwm)
+            # construct trytestring from python string
+            powed_txn_trytes = TryteString(powed_txn_string)
+
+            # Create powed txn object
+            # This method calculates the hash for the transaction
+            powed_txn = Transaction.from_tryte_string(
+                trytes=powed_txn_trytes
+            )
+            previoustx = powed_txn.hash
+            # put that back in the bundle
+            bundle.transactions[txn.current_index] = powed_txn
+
+            # Check for inconsistency in hash
+            hash_trits = powed_txn.hash.as_trits()
+            if hash_trits[-mwm:] == trailing_zeros:
+                # We are good to go, exit from while loop
+                break
             else:
-                raise ValueError('Tail transaction is inconsistent in bundle')
-
-        else: # It is not a tail transaction
-            txn.branch_transaction_hash = trunk_transaction_hash
-            txn.trunk_transaction_hash = previoustx # the previous transaction
-
-        # Let's do the pow locally
-        txn_string = txn.as_tryte_string().__str__()
-        # returns a python unicode string
-        powed_txn_string = get_powed_tx_trytes(txn_string, mwm)
-        # construct trytestring from python string
-        powed_txn_trytes = TryteString(powed_txn_string)
-        # compute transaction hash
-        hash_string = get_hash_trytes(powed_txn_string)
-        hash_trytes = TryteString(hash_string)
-        hash_= TransactionHash(hash_trytes)
-
-        # Create powed txn object
-        powed_txn = Transaction.from_tryte_string(
-            trytes=powed_txn_trytes,
-            hash_=hash_
-        )
+                i = i + 1
+                logger.info('Ooops, wrong hash detected in try'
+                    ' #{rounds}. Recalculating pow... '.format(rounds= i))
+
+        # Something really bad happened
+        if i == max_iter:
+            raise with_context(
+                exc=ValueError('PoW calculation failed for {max_iter} times.'
+                    ' Make sure that the transaction is valid: {tx}'.format(
+                    max_iter=max_iter,
+                    tx=powed_txn.as_json_compatible()
+                    )
+                ),
+                context={
+                    'original': txn,
+                },
+            )
 
-        previoustx = powed_txn.hash
-        # put that back in the bundle
-        bundle.transactions[txn.current_index] = powed_txn
     return bundle.as_tryte_strings()

setup.py

@@ -7,7 +7,7 @@
   name        = 'PyOTA-PoW',
   description = 'Ccurl PoW Interface for PyOTA',
   url         = 'https://github.com/iotaledger/ccurl.interface.py',
-  version     = '1.0.2',
+  version     = '1.1.0',
 
   long_description = long_description,
   packages=['pow'],