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fixes blockchain block listener #57

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Merged
xeroc merged 1 commit into from
Mar 14, 2018
Merged

fixes blockchain block listener #57

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48 changes: 44 additions & 4 deletions bitshares/blockchain.py
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Original file line number Diff line number Diff line change
Expand Up @@ -12,13 +12,16 @@ class Blockchain(object):
instance
:param str mode: (default) Irreversible block (``irreversible``) or
actual head block (``head``)
:param int max_block_wait_repetition: (default) 3 maximum wait time for next block
is max_block_wait_repetition * block_interval

This class let's you deal with blockchain related data and methods.
"""
def __init__(
self,
bitshares_instance=None,
mode="irreversible"
mode="irreversible",
max_block_wait_repetition=None
):
self.bitshares = bitshares_instance or shared_bitshares_instance()

Expand All @@ -29,6 +32,14 @@ def __init__(
else:
raise ValueError("invalid value for 'mode'!")

if max_block_wait_repetition:
self.max_block_wait_repetition = max_block_wait_repetition
else:
self.max_block_wait_repetition = 3

def is_irreversible_mode(self):
return self.mode == 'last_irreversible_block_num'

def info(self):
""" This call returns the *dynamic global properties*
"""
Expand Down Expand Up @@ -109,7 +120,7 @@ def blocks(self, start=None, stop=None):
confirmed by 2/3 of all block producers and is thus irreversible)
"""
# Let's find out how often blocks are generated!
block_interval = self.chainParameters().get("block_interval")
self.block_interval = self.chainParameters().get("block_interval")

if not start:
start = self.get_current_block_num()
Expand All @@ -126,7 +137,7 @@ def blocks(self, start=None, stop=None):
# Blocks from start until head block
for blocknum in range(start, head_block + 1):
# Get full block
block = self.bitshares.rpc.get_block(blocknum)
block = self.wait_for_and_get_block(blocknum)
block.update({"block_num": blocknum})
yield block
# Set new start
Expand All @@ -137,7 +148,36 @@ def blocks(self, start=None, stop=None):
return

# Sleep for one block
time.sleep(block_interval)
time.sleep(self.block_interval)

def wait_for_and_get_block(self, block_number, blocks_waiting_for=None):
""" Get the desired block from the chain, if the current head block is smaller (for both head and irreversible)
then we wait, but a maxmimum of blocks_waiting_for * max_block_wait_repetition time before failure.

:param int block_number: desired block number
:param int blocks_waiting_for: (default) difference between block_number and current head
how many blocks we are willing to wait, positive int
"""
if not blocks_waiting_for:
blocks_waiting_for = max(1, block_number - self.get_current_block_num())

repetition = 0
# can't return the block before the chain has reached it (support future block_num)
while self.get_current_block_num() < block_number:
repetition += 1
time.sleep(self.block_interval)
if repetition > blocks_waiting_for * self.max_block_wait_repetition:
raise Exception("Wait time for new block exceeded, aborting")
# block has to be returned properly
block = self.bitshares.rpc.get_block(block_number)
repetition = 0
while not block:
repetition += 1
time.sleep(self.block_interval)
if repetition > self.max_block_wait_repetition:
raise Exception("Wait time for new block exceeded, aborting")
block = self.bitshares.rpc.get_block(block_number)
return block

def ops(self, start=None, stop=None, **kwargs):
""" Yields all operations (including virtual operations) starting from
Expand Down