The merkle_parser module offers capability to compare and inspect Merkle tree data structures marshaled from a JMerkle process. Other producers can be utilized assuming they adhere to the established binary protocol. In order to avoid any unmarshaling overhead, the merkle_parser module uses bitstring matching against raw binary.
While this module's out-of-box Merkle tree parsing/comparison performance is already extremely fast, HiPE enabled environments will experience yet even better performance.
The merkle_parser module need only be compiled in order to start using it.
The compare and inspect operations are exported as diff/2 and allkeys/1 respectively.
- Comparing two merkle tree structures, Tree1 & Tree2, is done via
merkle_parser:diff(Tree1,Tree2).The diff/2 function will yield a list of leaves that differ between the two trees.
- Inspecting a merkle tree's contents is done via
merkle_parser:allkeys(Tree1).The allkeys/1 function will yield a list of all leaves of the given tree.
Here's a rudimentary example that inspects and compares trees marshaled from the jmerkle_sequential example:
-module(merkle_parser_demo).
-export([demo/0]).
%% Shows example usage on marshaled binary from the jmerkle_sequential example.
demo() ->
% the following file:read_file/1 operations assume java.io.tmpdir was simply "/tmp":
{ok, InitialInventoryTree} = file:read_file("/tmp/InitialInventoryTree.out"),
io:format("InitialInventoryTree: ~p~n", [InitialInventoryTree]),
% execute "allkeys" on the binary InitialInventoryTree:
InitialInventoryKeys = merkle_parser:allkeys(InitialInventoryTree),
io:format("InitialInventoryKeys: ~p~n", [InitialInventoryKeys]),
{ok, AlteredInventoryTree} = file:read_file("/tmp/AlteredInventoryTree.out"),
io:format("AlteredInventoryTree: ~p~n", [AlteredInventoryTree]),
% execute "allkeys" on the binary AlteredInventoryTree:
AlteredInventoryKeys = merkle_parser:allkeys(AlteredInventoryTree),
io:format("AlteredInventoryKeys: ~p~n", [AlteredInventoryKeys]),
% execute "diff" between the two binary Merkle trees:
Diff = merkle_parser:diff(InitialInventoryTree, AlteredInventoryTree),
io:format("Diff: ~p~n", [Diff]),
ok.The output from the io:format calls:
1> merkle_parser_demo:demo().
InitialInventoryTree: <<1,253,3,149,159,112,200,219,103,87,197,189,236,126,39,
194,184,136,192,17,134,0,0,0,192,0,5,184,0,91,168,142,
115,116,250,160,43,55,157,69,240,195,123,163,66,13,135,
66,198,0,0,0,7,119,105,100,103,101,116,48,16,0,165,232,
105,38,73,118,27,250,89,0,163,222,14,106,107,9,188,13,
199,63,0,0,0,7,119,105,100,103,101,116,51,43,0,131,224,
108,116,199,112,9,229,16,231,61,140,83,214,75,226,225,
96,10,113,0,0,0,7,119,105,100,103,101,116,49,84,0,203,
246,235,17,66,207,68,121,46,118,168,110,13,50,253,137,
249,73,53,169,0,0,0,7,119,105,100,103,101,116,50,112,0,
199,29,153,252,230,86,141,153,94,25,207,220,29,137,8,
146,179,152,228,112,0,0,0,7,119,105,100,103,101,116,52>>
InitialInventoryKeys: [<<"widget4">>,<<"widget2">>,<<"widget1">>,
<<"widget3">>,<<"widget0">>]
AlteredInventoryTree: <<1,208,246,170,194,137,215,193,114,189,228,122,86,10,
216,132,0,73,82,125,13,0,0,0,195,0,5,184,0,91,168,142,
115,116,250,160,43,55,157,69,240,195,123,163,66,13,135,
66,198,0,0,0,7,119,105,100,103,101,116,48,16,0,165,232,
105,38,73,118,27,250,89,0,163,222,14,106,107,9,188,13,
199,63,0,0,0,7,119,105,100,103,101,116,51,43,0,131,224,
108,116,199,112,9,229,16,231,61,140,83,214,75,226,225,
96,10,113,0,0,0,7,119,105,100,103,101,116,49,84,0,131,
224,108,116,199,112,9,229,16,231,61,140,83,214,75,226,
225,96,10,113,0,0,0,7,119,105,100,103,101,116,50,118,0,
234,85,245,122,169,76,116,169,44,122,147,178,86,137,0,
193,167,86,84,0,0,0,0,10,98,114,97,110,100,32,110,101,
119,33>>
AlteredInventoryKeys: [<<"brand new!">>,<<"widget2">>,<<"widget1">>,
<<"widget3">>,<<"widget0">>]
Diff: [<<"brand new!">>,<<"widget4">>,<<"widget2">>]
okAs you can see, the output is functionally equivalent to the jmerkle_sequential sample output.
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