4f5f3e30ea
Long story short: Once we create a server and start it, we can't start it again. We can't close it and restart it, and we can't just start it without closing it. Unfortunately, if the server's config needs to change, we have a Problem here. This ultimately means that the retry logic for GetListeners can't actually retry successfully; if we fail on the first attempt, we necessarily fail on any later attempts also, and if we try to fix that, we get panics. But! We don't actually NEED to retry. We just need to ensure that we can open a :0 port, extract the actual port number, and use that in places where the port number mattered, without having to rebind it. The only actual place we needed to rebind things was opening gRPC servers, so we introduce a gRPC Listener that can be used instead of trying to bind to a specified port. In a bunch of other cases where we had similar logic to try to allocate and then use a port, we can switch to just using a provided listener. For instance, net/http has `Serve(net.Listener, handler)`, not just ListenAndServe(addr, handler). This should eliminate the weird CI failures from eaddrinuse. NOT fixed: server/cluster_test.go/TestClusterResize_AddNode isn't working right now. The new node isn't actually being added to the existing cluster. I attempted this but was outsmarted by it, and I think fixing the rest of this is worth it as a separate thing. |
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|---|---|---|
| .. | ||
| cfg | ||
| array.go | ||
| cursor.go | ||
| cursor_internal_test.go | ||
| cursor_test.go | ||
| cursorx.go | ||
| db.go | ||
| db_test.go | ||
| dot.go | ||
| helpers_test.go | ||
| ingest_test.go | ||
| internal_test.go | ||
| page_map.go | ||
| rbf.go | ||
| rbf_test.go | ||
| README.md | ||
| tx.go | ||
| tx_test.go | ||
| util.go | ||
| util_test.go | ||
| vprint.go | ||
Roaring B-tree Format
The RBF format represents a Roaring bitmap whose containers are stored in the leafs of a b-tree. This allows the bitmap to be efficiently queried & updated.
File Format
The RBF file is divided into equal 8KB pages. Each page after the meta page is numbered incrementally from 1 to 1^31.
Pages can be one of the following types:
- Meta page: contains header information.
- Branch page: contains pointers to lower branch & leaf pages.
- Leaf page: contains array and RLE container data.
- Bitmap page: contains bitmap container data.
All integer values are little endian encoded.
Page header
Every page type except the bitmap page contains the following header:
Meta page
The meta page contains the following header:
[4] magic (\xFFRBF)
[4] flags
[4] page count
[8] wal ID
[4] root records pgno
[4] freelist pgno
Root Records page
A list of all b-tree names & their respective root page numbers are stored in root record pages. Once a bitmap root is created, it is never moved so the root record pages only need to be rewritten when creating, renaming, or deleting a b-tree. If records exceed the size of a page then they are overflowed to additional pages.
[4] page number
[4] flags
[4] overflow pgno
[*] bitmap records
Each bitmap record is represented as:
[4] pgno
[2] name size
[*] name
All bitmap records are loaded into memory when the file is opened.
Branch page
The branch page contains the following header:
[4] page number
[4] flags
[2] cell count
[*] cell index (2 * cell count)
[*] padding for 4-byte alignment
Each cell is formatted as:
[8] highbits
[4] flags
[4] page number
Leaf page
The leaf page contains the following header:
[4] page number
[4] flags
[2] cell count
[*] cell index (2 * cell count)
The leaf page contains a series of cells with the header of:
[8] highbits
[4] flag
[4] child count
[*] array or RLE data
Bitmap page
The data for the bitmap page takes up the entire 8KB.
Proof of Concept Notes
The following are notes made that are temporary for the RBF format. This will change as development progresses:
- Transaction support is deferred
- WAL support is deferred
Pattern of branch splits when adding data in ascending sorted order.
In this example, fan-out is restricted to 2 to make the drawings easy and the splits obvious. The data leaves are only allowed one roaring.Container key (ckey) in this example.
Each frame adds the next datum: A,B,C,D,E,... in order.
The letter represent data leaves, while numbers represent branch pages. The one exception is the first frame where the root is a leaf with data. Every frame after has normal branch at the root.
NB: there are only three places pages get written on addition: a) writeRoot b) putLeafCell c) putBranchCells
add A: root 3 A
add B: root 3 4 5 A B
add C: this sequence of updates occurs
-
putLeafCell writes leaf B to page 5
-
putLeafCell writes leaf C to page 6
-
putBranchCells writes branch page 7 with children 4,5
-
putBranchCells writes branch page 8 with child 6
-
writeRoot writes branch cells to pgno 3, children: 7,8
root 3 7 8 4 5 6 A B C
add D:
root
3
7 8
4 5 6 9
A B C D