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Document error codes of classic-level and many-level #20

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Merged
merged 2 commits into from
Mar 20, 2022
Merged

Document error codes of classic-level and many-level #20

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8c6c241
Document error codes of `classic-level` and `many-level`
vweevers Mar 12, 2022
c6d9d10
Remove now-unused `LEVEL_ASSERT` code
vweevers Mar 20, 2022
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30 changes: 29 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -78,9 +78,14 @@
- [`LEVEL_INVALID_KEY`](#level_invalid_key)
- [`LEVEL_INVALID_VALUE`](#level_invalid_value)
- [`LEVEL_CORRUPTION`](#level_corruption)
- [`LEVEL_IO_ERROR`](#level_io_error)
- [`LEVEL_INVALID_PREFIX`](#level_invalid_prefix)
- [`LEVEL_NOT_SUPPORTED`](#level_not_supported)
- [`LEVEL_LEGACY`](#level_legacy)
- [`LEVEL_LOCKED`](#level_locked)
- [`LEVEL_READONLY`](#level_readonly)
- [`LEVEL_CONNECTION_LOST`](#level_connection_lost)
- [`LEVEL_REMOTE_ERROR`](#level_remote_error)
- [Shared Access](#shared-access)
- [Private API For Implementors](#private-api-for-implementors)
- [Example](#example)
Expand Down Expand Up @@ -809,7 +814,10 @@ try {
await db.open()
} catch (err) {
console.error(err.code) // 'LEVEL_DATABASE_NOT_OPEN'
console.error(err.cause) // 'Error: Failed to acquire lock'

if (err.cause && err.cause.code === 'LEVEL_LOCKED') {
// Another process or instance has opened the database
}
}
```

Expand Down Expand Up @@ -864,6 +872,10 @@ When a value is `null`, `undefined` or (if an implementation deems it so) otherw

Data could not be read (from an underlying store) due to a corruption.

#### `LEVEL_IO_ERROR`

Data could not be read (from an underlying store) due to an input/output error, for example from the filesystem.

#### `LEVEL_INVALID_PREFIX`

When a sublevel prefix contains characters outside of the supported byte range.
Expand All @@ -890,6 +902,22 @@ module.exports = function plugin (db) {

When a method, option or other property was used that has been removed from the API.

#### `LEVEL_LOCKED`

When an attempt was made to open a database that is already open in another process or instance. Used by `classic-level` and other implementations of `abstract-level` that use exclusive locks.

#### `LEVEL_READONLY`

When an attempt was made to write data to a read-only database. Used by `many-level`.

#### `LEVEL_CONNECTION_LOST`

When a database relies on a connection to a remote party and that connection has been lost. Used by `many-level`.

#### `LEVEL_REMOTE_ERROR`

When a remote party encountered an unexpected condition that it can't reflect with a more specific code. Used by `many-level`.

### Shared Access

Unless documented otherwise, implementations of `abstract-level` do _not_ support accessing a database from multiple processes running in parallel. That includes Node.js clusters and Electron renderer processes.
Expand Down