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diff --git a/src/c/liberasurecode/README.md b/src/c/liberasurecode/README.md deleted file mode 100644 index efff171..0000000 --- a/src/c/liberasurecode/README.md +++ /dev/null @@ -1,406 +0,0 @@ -liberasurecode -============== - -liberasurecode is an Erasure Code API library written in C with pluggable Erasure Code backends. - ----- - -Highlights -========== - - * Unified Erasure Coding interface for common storage workloads. - - * Pluggable Erasure Code backends - As of v1.0, liberasurecode supports the following backends: - - - 'Jerasure' - Erasure Coding library that supports Reed-Solomon, Cauchy backends [1] - - 'ISA-L' - Intel Storage Acceleration Library - SIMD accelerated Erasure Coding backends [2] - - 'SHSS' - NTT Lab Japan's hybrid Erasure Coding backend [4] - - 'Flat XOR HD' - built-in to liberasurecode, based on [3] - - 'NULL' template backend implemented to help future backend writers - - - * True 'plugin' architecture - liberasurecode uses Dynamically Loaded (DL) libraries to realize a true 'plugin' architecture. This also allows one to build liberasurecode indepdendent of the Erasure Code backend libraries. - - * Cross-platform - liberasurecode is known to work on Linux (Fedora/Debian flavors), Solaris, BSD and Darwin/Mac OS X. - - * Community support - Developed alongside Erasure Code authority Kevin Greenan, liberasurecode is an actively maintained open-source project with growing community involvement (Openstack Swift, Ceph, PyECLib). - ----- - -License -========== - -liberasurecode is distributed under the terms of the **BSD** license. - ----- - -Active Users -==================== - - * PyECLib - Python EC library: https://pypi.python.org/pypi/PyECLib - * Openstack Swift Object Store - https://wiki.openstack.org/wiki/Swift - ----- - -liberasurecode API Definition -============================= - -``` c - -/* liberasurecode frontend API functions */ - -/** - * Create a liberasurecode instance and return a descriptor - * for use with EC operations (encode, decode, reconstruct) - * - * @param id - one of the supported backends as - * defined by ec_backend_id_t - * @param ec_args - arguments to the EC backend - * arguments common to all backends - * k - number of data fragments - * m - number of parity fragments - * w - word size, in bits - * hd - hamming distance (=m for Reed-Solomon) - * ct - fragment checksum type (stored with the fragment metadata) - * backend-specific arguments - * null_args - arguments for the null backend - * flat_xor_hd, jerasure do not require any special args - * - * @return liberasurecode instance descriptor (int > 0) - */ -int liberasurecode_instance_create(const ec_backend_id_t id, - struct ec_args *args); - -/** - * Close a liberasurecode instance - * - * @param desc - liberasurecode descriptor to close - * - * @return 0 on success, otherwise non-zero error code - */ -int liberasurecode_instance_destroy(int desc); - - -/** - * Erasure encode a data buffer - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * @param orig_data - data to encode - * @param orig_data_size - length of data to encode - * @param encoded_data - pointer to _output_ array (char **) of k data - * fragments (char *), allocated by the callee - * @param encoded_parity - pointer to _output_ array (char **) of m parity - * fragments (char *), allocated by the callee - * @param fragment_len - pointer to _output_ length of each fragment, assuming - * all fragments are the same length - * - * @return 0 on success, -error code otherwise - */ -int liberasurecode_encode(int desc, - const char *orig_data, uint64_t orig_data_size, /* input */ - char ***encoded_data, char ***encoded_parity, /* output */ - uint64_t *fragment_len); /* output */ - -/** - * Cleanup structures allocated by librasurecode_encode - * - * The caller has no context, so cannot safely free memory - * allocated by liberasurecode, so it must pass the - * deallocation responsibility back to liberasurecode. - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * @param encoded_data - (char **) array of k data - * fragments (char *), allocated by liberasurecode_encode - * @param encoded_parity - (char **) array of m parity - * fragments (char *), allocated by liberasurecode_encode - * - * @return 0 in success; -error otherwise - */ -int liberasurecode_encode_cleanup(int desc, char **encoded_data, - char **encoded_parity); - -/** - * Reconstruct original data from a set of k encoded fragments - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * @param fragments - erasure encoded fragments (> = k) - * @param num_fragments - number of fragments being passed in - * @param fragment_len - length of each fragment (assume they are the same) - * @param force_metadata_checks - force fragment metadata checks (default: 0) - * @param out_data - _output_ pointer to decoded data - * @param out_data_len - _output_ length of decoded output - * (both output data pointers are allocated by liberasurecode, - * caller invokes liberasurecode_decode_clean() after it has - * read decoded data in 'out_data') - * - * @return 0 on success, -error code otherwise - */ -int liberasurecode_decode(int desc, - char **available_fragments, /* input */ - int num_fragments, uint64_t fragment_len, /* input */ - int force_metadata_checks, /* input */ - char **out_data, uint64_t *out_data_len); /* output */ - -/** - * Cleanup structures allocated by librasurecode_decode - * - * The caller has no context, so cannot safely free memory - * allocated by liberasurecode, so it must pass the - * deallocation responsibility back to liberasurecode. - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * @param data - (char *) buffer of data decoded by librasurecode_decode - * - * @return 0 on success; -error otherwise - */ -int liberasurecode_decode_cleanup(int desc, char *data); - -/** - * Reconstruct a missing fragment from a subset of available fragments - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * @param available_fragments - erasure encoded fragments - * @param num_fragments - number of fragments being passed in - * @param fragment_len - size in bytes of the fragments - * @param destination_idx - missing idx to reconstruct - * @param out_fragment - output of reconstruct - * - * @return 0 on success, -error code otherwise - */ -int liberasurecode_reconstruct_fragment(int desc, - char **available_fragments, /* input */ - int num_fragments, uint64_t fragment_len, /* input */ - int destination_idx, /* input */ - char* out_fragment); /* output */ - -/** - * Return a list of lists with valid rebuild indexes given - * a list of missing indexes. - * - * @desc: liberasurecode instance descriptor (obtained with - * liberasurecode_instance_create) - * @fragments_to_reconstruct list of indexes to reconstruct - * @fragments_to_exclude list of indexes to exclude from - * reconstruction equation - * @fragments_needed list of fragments needed to reconstruct - * fragments in fragments_to_reconstruct - * - * @return 0 on success, non-zero on error - */ -int liberasurecode_fragments_needed(int desc, - int *fragments_to_reconstruct, - int *fragments_to_exclude, - int *fragments_needed); - -``` - -Erasure Code Fragment Checksum Types Supported ----------------------------------------------- - -``` c - -/* Checksum types supported for fragment metadata stored in each fragment */ -typedef enum { - CHKSUM_NONE = 0, /* "none" (default) */ - CHKSUM_CRC32 = 1, /* "crc32" */ - CHKSUM_TYPES_MAX, -} ec_checksum_type_t; - -``` - -Erasure Code Fragment Checksum API ----------------------------------- - -``` c - -struct __attribute__((__packed__)) -fragment_metadata -{ - uint32_t idx; /* 4 */ - uint32_t size; /* 4 */ - uint32_t frag_backend_metadata_size; /* 4 */ - uint64_t orig_data_size; /* 8 */ - uint8_t chksum_type; /* 1 */ - uint32_t chksum[LIBERASURECODE_MAX_CHECKSUM_LEN]; /* 32 */ - uint8_t chksum_mismatch; /* 1 */ - uint8_t backend_id; /* 1 */ - uint32_t backend_version; /* 4 */ -} fragment_metadata_t; - -#define FRAGSIZE_2_BLOCKSIZE(fragment_size) \ - (fragment_size - sizeof(fragment_header_t)) - -/** - * Get opaque metadata for a fragment. The metadata is opaque to the - * client, but meaningful to the underlying library. It is used to verify - * stripes in verify_stripe_metadata(). - * - * @param fragment - fragment data pointer - * @param fragment_metadata - pointer to allocated buffer of size at least - * sizeof(struct fragment_metadata) to hold fragment metadata struct - * - * @return 0 on success, non-zero on error - */ -//EDL: This needs to be implemented -int liberasurecode_get_fragment_metadata(char *fragment, - fragment_metadata_t *fragment_metadata); - -/** -* Verify that the specified pointer points to a well formed fragment that can -* be processed by both this instance of liberasurecode and the specified -* backend. -* -* @param desc - liberasurecode descriptor/handle -* from liberasurecode_instance_create() -* @param fragment - fragment to verify -* -* @return 1 if fragment validation fails, 0 otherwise. -*/ -int is_invalid_fragment(int desc, char *fragment); - -/** - * Verify a subset of fragments generated by encode() - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * @param fragments - fragments part of the EC stripe to verify - * @param num_fragments - number of fragments part of the EC stripe - * - * @return 1 if stripe checksum verification is successful, 0 otherwise - */ -int liberasurecode_verify_stripe_metadata(int desc, - char **fragments, int num_fragments); - -/* ==~=*=~===~=*=~==~=*=~== liberasurecode Helpers ==~*==~=*=~==~=~=*=~==~= */ - -/** - * This computes the aligned size of a buffer passed into - * the encode function. The encode function must pad fragments - * to be algined with the word size (w) and the last fragment also - * needs to be aligned. This computes the sum of the algined fragment - * sizes for a given buffer to encode. - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * @param data_len - original data length in bytes - * - * @return aligned length, or -error code on error - */ -int liberasurecode_get_aligned_data_size(int desc, uint64_t data_len); - -/** - * This will return the minimum encode size, which is the minimum - * buffer size that can be encoded. - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * - * @return minimum data length length, or -error code on error - */ -int liberasurecode_get_minimum_encode_size(int desc); - -/** - * This will return the fragment size, which is each fragment data - * length the backend will allocate when encoding. - * - * @param desc - liberasurecode descriptor/handle - * from liberasurecode_instance_create() - * @param data_len - original data length in bytes - * - * @return fragment size - sizeof(fragment_header) + size - * + frag_backend_metadata_size - */ -int liberasurecode_get_fragment_size(int desc, int data_len); -``` ----- - - -Build and Install -================= - -To build the liberasurecode repository, perform the following from the -top-level directory: - -``` sh - $ ./autogen.sh - $ ./configure - $ make - $ make test - $ sudo make install -``` - ----- - -Code organization -================= -``` - |-- include - | +-- erasurecode - | | +-- erasurecode.h --> liberasurecode frontend API header - | | +-- erasurecode_backend.h --> liberasurecode backend API header - | +-- xor_codes --> headers for the built-in XOR codes - | - |-- src - | |-- erasurecode.c --> liberasurecode API implementation - | | (frontend + backend) - | |-- backends - | | +-- null - | | +--- null.c --> 'null' erasure code backend (template backend) - | | +-- xor - | | +--- flat_xor_hd.c --> 'flat_xor_hd' erasure code backend (built-in) - | | +-- jerasure - | | +-- jerasure_rs_cauchy.c --> 'jerasure_rs_vand' erasure code backend (jerasure.org) - | | +-- jerasure_rs_vand.c --> 'jerasure_rs_cauchy' erasure code backend (jerasure.org) - | | +-- isa-l - | | +-- isa_l_rs_vand.c --> 'isa_l_rs_vand' erasure code backend (Intel) - | | +-- shss - | | +-- shss.c --> 'shss' erasure code backend (NTT Labs) - | | - | |-- builtin - | | +-- xor_codes --> XOR HD code backend, built-in erasure - | | | code implementation (shared library) - | | +-- xor_code.c - | | +-- xor_hd_code.c - | | - | +-- utils - | +-- chksum --> fragment checksum utils for erasure - | +-- alg_sig.c coded fragments - | +-- crc32.c - | - |-- doc --> API Documentation - | +-- Doxyfile - | +-- html - | - |--- test --> Test routines - | +-- builtin - | | +-- xor_codes - | +-- liberasurecode_test.c - | +-- utils - | - |-- autogen.sh - |-- configure.ac - |-- Makefile.am - |-- README - |-- NEWS - |-- COPYING - |-- AUTHORS - |-- INSTALL - +-- ChangeLog -``` ---- - -References -========== - - [1] Jerasure, C library that supports erasure coding in storage applications, http://jerasure.org - - [2] Intel(R) Storage Acceleration Library (Open Source Version), https://01.org/intel%C2%AE-storage-acceleration-library-open-source-version - - [3] Greenan, Kevin M et al, "Flat XOR-based erasure codes in storage systems", http://www.kaymgee.com/Kevin_Greenan/Publications_files/greenan-msst10.pdf - - [4] Kota Tsuyuzaki <tsuyuzaki.kota@lab.ntt.co.jp>, Ryuta Kon <kon.ryuta@po.ntts.co.jp>, "NTT SHSS Erasure Coding backend" |