diff options
Diffstat (limited to 'proposals')
| -rw-r--r-- | proposals/0004-hyperdb.md | 23 |
1 files changed, 11 insertions, 12 deletions
diff --git a/proposals/0004-hyperdb.md b/proposals/0004-hyperdb.md index d551b64..393c997 100644 --- a/proposals/0004-hyperdb.md +++ b/proposals/0004-hyperdb.md @@ -52,7 +52,7 @@ this abstraction layer. *This section describes Hyperdb's interface and behavior in the abstract for application programmers. It is not intended to be exact documentation of any -particular implementation (including the reference Javascript module).* +particular implementation (including the reference JavaScript module).* Hyperdb is structured to be used much like a traditional hierarchical filesystem. A value can be written and read at locations like `/foo/bar/baz`, @@ -82,7 +82,7 @@ equivalent. A key can be both a "path segment" and key at the same time; e.g., **Values** can be any binary blob, including empty (of zero length). For example, values could be UTF-8 encoded strings, JSON encoded objects, protobuf -messages, or a raw `uint64` integer (of either endian-ness). Length is the only +messages, or a raw `uint64` integer (of either endianness). Length is the only form of type or metadata stored about the value; deserialization and validation are left to library and application developers. @@ -149,7 +149,7 @@ The Entry protobuf message schema is: message Feed { required bytes key = 1; } - + required string key = 1; optional bytes value = 2; required bytes trie = 3; @@ -159,9 +159,8 @@ The Entry protobuf message schema is: optional bytes contentFeed = 7; } -Some fields are are specific to the multi-writer features described in their -own DEP and mentioned only partially here. The fields common to both message -types are: +Some fields are specific to the multi-writer features described in their own DEP +and mentioned only partially here. The fields common to both message types are: - `key`: UTF-8 key that this node describes. Leading and trailing forward slashes (`/`) are always stripped before storing in protobuf. @@ -194,7 +193,7 @@ must be defined, so the new message can be referred to via `inflated`. In this case the entry is refereed to as an "inflated entry". -## Path Hashing +## Path Hashing [path_hashing]: #path_hashing Every key path has component-wise fixed-size hash representation that is used @@ -202,7 +201,7 @@ by the trie. The concatenation of all path hashes yields a "path hash array" for the entire key. Note that analogously to a hash map data structure, there can be more than one key (string) with the same key hash in the same database with no problems: the hash points to a linked-list "bucket" of Entries, which -can be iterated over linearly to find the correct value. +can be iterated over linearly to find the correct value. The path hash is represented by an array of bytes. Elements are 2-bit encoded (values 0, 1, 2, 3), except for an optional terminating element which has value @@ -218,7 +217,7 @@ algorithm is included in the libsodium library in the form of the `crypto_shorthash()` function. A 16-byte "secret" key is required; for this use case we use all zeros. -When converting the 8-bytehash to an array of 2-bit bytes, the ordering is +When converting the 8-byte hash to an array of 2-bit bytes, the ordering is proceed byte-by-byte, and for each take the two lowest-value bits (aka, `hash & 0x3`) as byte index `0`, the next two bits (aka, `hash & 0xC`) as byte index `1`, etc. When concatenating path hashes into a longer array, the first @@ -502,7 +501,7 @@ Now we `db.put('/a/c', 'hello')` and expect a second Entry: { key: 'a/c', value: 'hello', trie: - [ , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , + [ , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , { element: 2, feed: 0, index: 0 } ] } ``` @@ -600,7 +599,7 @@ is: ``` { key: 'a/c', value: , - trie: [ , { val: 1, feed: 0, index: 2 }, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , + trie: [ , { val: 1, feed: 0, index: 2 }, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , { val: 1, feed: 0, index: 0 } ] } ``` @@ -747,7 +746,7 @@ concerns are explicitly out of scope for this DEP. [changelog]: #changelog As of March 2018, Mathias Buus (@mafintosh) is leading development of a hyperdb -nodejs module on [github](https://github.com/mafintosh/hyperdb), which is the +Node.js module on [github](https://github.com/mafintosh/hyperdb), which is the basis for this DEP. - 2017-12-06: Stephen Whitmore (@noffle) publishes `ARCHITECTURE.md` overview |