Gevent based distributed hash table
Project description
This is a basic implementation of a dht using gevent.
There are two things you have to concern yourself with.
1.) Bootstrapping the network.
The following example creates a network of one node
-------------------------------------------------------------------
import gevent_dht
table = gevent_dht.distributedHashTable(None) #This tell the network it
# is the first node by default it listens on port 8339
#
table['key_1'] = [1,2,3] #This sets a value in our hash table
for i in table['key_1']:
print i #Prints 123
table.append('key_1', 4) #Adds an item to a list in a hash table
#Note if the key is not in the hash table
#It will put a list in place and then append
#to it.
#Now we are adding another node
other_clients_table = gevent_dht.distributedHashTable(
'127.0.0.1:8339', local_port = 8449)
#Another client has connected. It supplied the address of
# a node in the network to connect with the preexisting network
for i in other_clients_table['key_1']:
print i #Prints 1234
-------------------------------------------------------------------
So in order to connect to an existing network you must have a way to get an
address of another member. It doesn't have to be the first node but needs
to be a node in the network.
2.) Latency/ This may fail.
Keys are not guarenteed to persist forever, nodes may crash, the network
may eat messages etc... While we are working in tcp/ip mode there may still
be bizarre glitches. Always check for a return value of None.
Additionally due to the time it takes for messages to travel the network
sometimes a key will not be immedietly available after you set it or
when you get the result back it may not be completely current.
There are two things you have to concern yourself with.
1.) Bootstrapping the network.
The following example creates a network of one node
-------------------------------------------------------------------
import gevent_dht
table = gevent_dht.distributedHashTable(None) #This tell the network it
# is the first node by default it listens on port 8339
#
table['key_1'] = [1,2,3] #This sets a value in our hash table
for i in table['key_1']:
print i #Prints 123
table.append('key_1', 4) #Adds an item to a list in a hash table
#Note if the key is not in the hash table
#It will put a list in place and then append
#to it.
#Now we are adding another node
other_clients_table = gevent_dht.distributedHashTable(
'127.0.0.1:8339', local_port = 8449)
#Another client has connected. It supplied the address of
# a node in the network to connect with the preexisting network
for i in other_clients_table['key_1']:
print i #Prints 1234
-------------------------------------------------------------------
So in order to connect to an existing network you must have a way to get an
address of another member. It doesn't have to be the first node but needs
to be a node in the network.
2.) Latency/ This may fail.
Keys are not guarenteed to persist forever, nodes may crash, the network
may eat messages etc... While we are working in tcp/ip mode there may still
be bizarre glitches. Always check for a return value of None.
Additionally due to the time it takes for messages to travel the network
sometimes a key will not be immedietly available after you set it or
when you get the result back it may not be completely current.
Project details
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