class Aws::TreeHash
Used for computing a tree hash SHA256 checksum of an object.
tree_hash = TreeHash.new tree_hash.update(file.read(1024 * 1024)) until file.eof? tree_hash.digest
Limitations and Notes¶ ↑
There are two main limitations to be aware of when using TreeHash:
-
TreeHash is not thread safe. Use multiple TreeHash objects to concurrently compute a tree hash of a large object. Join their hashes at the end into a single TreeHash and then call {#digest}
TreeHash.new(tree_hashes.map(&:hashes).flatten)
-
You must call {#update} with 1MB chunks of data. Only the final chunk may be smaller than 1MB.
If you have a large object/file, and you would like to compute the chunks concurrently, you must break the original file/data into sections that are evenly divisible by 1MB. Each section of data requires a seperate TreeHash object to compute hashes. Once all sections of data are complete, you can rejoin their {#hashes} in sequential order into a single TreeHash, then call {#digest} on the final tree hash.
Attributes
@return [Array<String>] The built up list of hashes. Each hash is
a sha255 digest of a 1MB chunk.
Public Class Methods
# File lib/aws-sdk-core/tree_hash.rb, line 33 def initialize(hashes = []) @digest = OpenSSL::Digest.new('sha256') @hashes = hashes end
Public Instance Methods
# File lib/aws-sdk-core/tree_hash.rb, line 50 def digest hashes = @hashes digest = OpenSSL::Digest.new('sha256') until hashes.count == 1 hashes = hashes.each_slice(2).map do |h1,h2| digest.reset if h2 digest.update(h1) digest.update(h2) digest.digest else h1 end end end hashes.first.bytes.map{|x| x.to_i.to_s(16).rjust(2, '0')}.join('') end
@param [String] chunk @return [String] Returns the computed SHA256 digest of the chunk.
# File lib/aws-sdk-core/tree_hash.rb, line 44 def update(chunk) @hashes << @digest.update(chunk).digest @digest.reset @hashes.last end