Method and system for object-based transactions in a storage system

1. A non-transitory computer readable medium comprising instructions, which when executed by a processor, perform a method, the method comprising:

creating a transaction object for a transaction, wherein the transaction object is identified by a transaction object ID (TOI) and associated with an object identified by an object ID (OID);

storing, in persistent storage, a first table of contents entry (TE) and a metadata (MD) frag for the transaction object, wherein the first TE references the MD frag and the MD frag identifies the object;

receiving a write request to write data to the transaction object as part of the transaction, wherein the write request specifies the TOI and an offset;

in response to the write request:

storing, in the persistent storage, a second TE and a data frag, wherein the second TE specifies the TOI and offset, and wherein the second TE references the data frag and the data frag comprises the data;

storing, in an in-memory data structure, an entry comprising a hash value and a physical address of the data frag, wherein the hash value is derived from the TOI and the offset;

receiving a commit request to commit the transaction;

in response to the commit request:

storing, in persistent storage, a third TE and a second metadata (MD) frag for the transaction object, wherein third TE references the second MD frag, wherein the second MD frag identifies the object and specifies that the transaction is committed;

updating, in the in-memory data structure, a second entry comprising a second hash value and a second physical address for a second data frag to replace the second physical address with the physical address, wherein the second hash value is derived from the OID and the offset.

2. The non-transitory computer readable medium of claim 1 , wherein prior to the commit request being processed, data in the object is accessible using the OID and the offset and the data in the data frag associated with the transaction, but not committed, is accessible using the TOI and the offset.

3. The non-transitory computer readable medium of claim 2 , wherein after the commit request is processed, the data in the data frag is accessible using the OID and the offset and second data in the second data frag is not accessible.

4. The non-transitory computer readable medium of claim 1 , wherein the persistent storage is solid-state memory.

5. The non-transitory computer readable medium of claim 1 , wherein the commit request specifies the TOI and does not specify the OID.

6. The non-transitory computer readable medium of claim 1 , wherein storing the TE comprises storing the TE in a table of contents (TOC) page in the persistent storage.

7. The non-transitory computer readable medium of claim 1 , wherein TE and the MD frag are stored in separate pages in a block in the persistent storage.

8. The non-transitory computer readable medium of claim 1 , wherein the MD frag identifies the object using the OID.

9. The non-transitory computer readable medium of claim 1 , wherein prior to processing the commit request, the MD frag specifies that the transaction is not committed.

10. The non-transitory computer readable medium of claim 1 , wherein the TE includes a third offset equal to −1.

11. A non-transitory computer readable medium comprising instructions, which when executed by a processor, perform a method, the method comprising:

receiving a write request to write data as part of a transaction, wherein the write request specifies a transaction object ID (TOI) for a transaction object and an offset, and wherein the TOI is associated with an object identified by an object ID (OID);

in response to the write request:

storing, in persistent storage, a first TE and a data frag, wherein TE specifies the TOI and the offset, wherein the first TE references the data frag and the data frag comprises the data;

storing, in an in-memory data structure, an entry comprising a hash value and a physical address of the data frag, wherein the hash value is derived from the TOI and the offset;

receiving a second write request to write second data as part of a second transaction, wherein the second write request specifies the second TOI for a second transaction object and a second offset and wherein the second TOI is associated with a second object identified by a second OID;

in response to the second write request:

storing, in the persistent storage, a second TE and a second data frag, wherein second TE specifies the second TOI and the second offset, wherein the second TE references the second data frag and the second data frag comprises the second data;

storing, in an in-memory data structure, a second entry comprising a second hash value and a second physical address of the second data frag, wherein the second hash value is derived from the second TOI and the second offset;

receiving a commit request, wherein the commit request comprises the TOI and the second TOI;

in response to the commit request:

storing, in persistent storage, a third TE and a compound frag, wherein third TE references the compound frag, wherein the compound frag comprises a fourth TE and a fifth TE, wherein the fourth TE references a MD frag, wherein the MD frag identifies the TOI and specifies that the transaction is committed, wherein the fifth TE references a second MD frag, wherein the second MD frag identifies the second TOI and specifies that the second transaction is committed;

updating, in the in-memory data structure, a third entry comprising a third hash value and a third physical address for a third data frag to replace the third physical address with the physical address, wherein the third hash value is derived from the OID and the offset;

updating, in the in-memory data structure, a fourth entry comprising a fourth hash value and a fourth physical address for a fourth data frag to replace the fourth physical address with the second physical address, wherein the fourth hash value is derived from the second OID and the second offset.

12. The non-transitory computer readable medium of claim 11 , the method further comprising:

prior to receiving the write request:

creating the transaction object;

storing, in the persistent storage, a sixth TE and a third MD frag for the transaction object, wherein the sixth TE references the third MD frag and the third MD frag identifies the object;

creating the second transaction object;

storing, in the persistent storage, a seventh TE and a fourth MD frag for the second transaction object, wherein the seventh TE references the fourth MD frag and the fourth MD frag identifies the second object.

13. The non-transitory computer readable medium of claim 11 , wherein the compound frag is stored in a frag page.

14. The non-transitory computer readable medium of claim 13 , wherein the third TE is stored in a table of contents page.

15. The non-transitory computer readable medium of claim 13 , wherein the frag page and the TOC page are stored in a block in the persistent storage.

16. The non-transitory computer readable medium of claim 11 , wherein the third TE specifies a type of frag with which the third TE is associated.

17. The non-transitory computer readable medium of claim 11 , wherein the third TE comprises a compound object ID and a fifth offset.

18. The non-transitory computer readable medium of claim 11 , wherein the fifth offset is −1.