FFI-based facebook Zstandard binding for LuaJIT.
- Installation
- Methods
- zstd.compressor.new
- zstd.compressor.version
- zstd.compressor:free
- zstd.compressor:load_dictionary
- zstd.compressor:unload_dictionary
- zstd.compressor:compress
- zstd.compressor:end_stream
- zstd.compressor:compress_file
- zstd.decompressor.new
- zstd.decompressor.version
- zstd.decompressor:free
- zstd.decompressor:load_dictionary
- zstd.decompressor:unload_dictionary
- zstd.decompressor:decompress
- zstd.decompressor:decompress_file
- Example
- Reference
Require Zstandard version above v1.5.0, to install Zstandard shared libraries, please check here.
To install this project, placing zstd/*.lua to your lua library path.
syntax: compressor, err = zstd.compressor.new(opts?)
The parameter opts accepts an optional table to constraint the behaviour of compressor.
opts.clevel: set compression level, acceptable values are in the range from 1 to ZSTD_maxCLevel(22), defaults to ZSTD_defaultCLevel(3).opts.dictionary: set dictionary use to compress.opts.use_raw: set the flag to check if the dictionary matches Zstandard's specification.falsewill use the dictionary matches Zstandard's specification ONLY,truewill use the dictionary doesn't match Zstandard's specification ONLY.
syntax: version = zstd.compressor.version()
Return the version of Zstandard shared lib.
syntax: err = zstd.compressor:free()
Free the internal stream object.
syntax: err = zstd.compressor:load_dictionary(data)
Set a new dictionary for the compressor, the exist use_raw options still take effect in new dictionary.
syntax: err = zstd.compressor:unload_dictionary()
Unload the compressor's dictionary.
syntax: output, err = zstd.compressor:compress(input)
Compresses the input data into the output data.
syntax: output, err = zstd.compressor:end_stream()
Pass the ZSTD_e_end flag to the internal stream.
syntax: err = zstd.compressor:compress_file(file)
Compress the file and save it into a new file named with the zst suffix.
syntax: decompressor, err = zstd.decompressor.new(opts?)
The parameter opts accepts an optional table to constraint the behaviour of decompressor.
opts.dictionary: set dictionary use to compress.opts.use_raw: set the flag to check if the dictionary matches Zstandard's specification.falsewill use the dictionary matches Zstandard's specification ONLY,truewill use the dictionary doesn't match Zstandard's specification ONLY.
syntax: version = zstd.decompressor.version()
Return the version of Zstandard shared lib.
syntax: err = zstd.decompressor:free()
Free the internal stream object.
syntax: err = zstd.decompressor:load_dictionary(data)
Set a new dictionary for the decompressor, the exist use_raw options still take effect in new dictionary.
syntax: err = zstd.decompressor:unload_dictionary()
Unload the decompressor's dictionary.
syntax: output, err = zstd.decompressor:decompress(input)
Decompresses the input data into the output data.
syntax: err = zstd.decompressor:decompress_file(in_file, out_file?)
Decompresses the file and saves it into a new file named as the parameter if the parameter is available; otherwise, it will try to name it with the original filename, removing the zst suffix.
file_path_to_compress = "file_path_to_compress"
file_path_to_decompress = "file_path_to_decompress" -- normally named like "file.zst"
dictionary_file_path = "dictionary_file_path"
-- compress file
compressor = require("zstd.compressor").new()
compressor:compress_file(file_path_to_compress)
-- decompress file
decompressor = require("zstd.decompressor").new()
decompressor:decompress_file(file_path_to_decompress)
-- compress with compress level and dictionary
dict = io.open(dictionary_file_path, "rb")
dict_data = dict:read("*a")
dict:close()
compressor = require("zstd.compressor").new({ clevel = 10, dictionary = dict_data })
compressor:compress_file(file_path_to_compress)
-- if the used dictionary does not match Zstandard's specification, pass the use_raw options
compressor = require("zstd.compressor").new({ clevel = 10, dictionary = dict_data, use_raw = true })
compressor:compress_file(file_path_to_compress)location / {
header_filter_by_lua_block {
local accept_zstd
if ngx.var.http_content_encoding then
return
end
local accept_encoding = ngx.var.http_accept_encoding
if accept_encoding and string.find(accept_encoding, "zstd") then
accept_zstd = true
end
if accept_zstd then
local compressor, err = require("zstd.compressor").new()
if not err then
ngx.header.content_length = nil
ngx.header["Content-Encoding"] = "zstd"
ngx.ctx.accept_zstd = accept_zstd
ngx.ctx.compressor = compressor
end
end
}
body_filter_by_lua_block {
if not ngx.ctx.accept_zstd then
return
end
local chunk, eof = ngx.arg[1], ngx.arg[2]
local compressor = ngx.ctx.compressor
if type(chunk) == "string" and chunk ~= "" then
local encode_chunk = compressor:compress(chunk)
ngx.arg[1] = encode_chunk
end
if eof then
local end_chunk = compressor:end_stream()
ngx.arg[1] = ngx.arg[1] .. end_chunk
compressor:free()
end
}
}See here.