Summary:
I added max_size option in blobstore. Since we now know the maximum number of buckets we'll ever use, we can allocate an array of buckets and access its elements without use of any locks! Common case Get doesn't lock anything now.
Benchmarks on 16KB block size show no impact on speed, though.
Test Plan: unittests + benchmark
Reviewers: dhruba, haobo, kailiu
Reviewed By: dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D13641
Summary:
I have implemented a FreeList version that supports fragmented blob chunks. Each block gets allocated and freed in FIFO order. Since the idea for the blocks to be big, we will not take a big hit of non-sequential IO. Free list is also faster, taking only O(k) size in both free and allocate instead of O(N) as before.
See more info on the task: https://our.intern.facebook.com/intern/tasks/?t=2990558
Also, I'm taking Slice instead of const char * and size in Put function.
Test Plan: unittests
Reviewers: haobo, kailiu, dhruba, emayanke
Reviewed By: dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D13569
Summary:
Developing a capability for storing values on external backing file(s).
This is just a highly unoptimized first pass - supports:
1) Allocating some portion of external file to be used to store value
2) Freeing the range, enabling it to be reused by other values
As next steps, I plan to:
1) Create some kind of stress testing. Once I can measure stuff, I can focus on optimizing.
2) Optimize locking.
3) Optimize freelist data structure. Currently we have O(n) for both freeing and allocation.
4) Figure out how to do recovery.
Test Plan: Created a unit test.
Reviewers: dhruba, haobo, kailiu
Reviewed By: dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D13389
