85 lines
2.8 KiB
Markdown
85 lines
2.8 KiB
Markdown
# imag-ruby
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A Ruby gem for scripting imag modules.
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## How does this work?
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Well, as we have some problems with lifetimes here, we have a fairly complex
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codebase in this crate.
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### The Problem
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The Problem is, that `libimagstore::store::FileLockEntry<'a>` has a lifetime. If
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we would wrap this object into a ruru wrapper and pass to the Ruby code, we
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couldn't guarantee anymore that the lifetime holds.
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The problem is simple, you see...
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### The solution?
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Never pass anything to the Ruby code.
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Yes, exactly. The Ruby code only sees 'handles'. It never actually gets the
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`Store` object either.
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We move the `Store` Object into a `Cache` object (actually, the Ruby code could
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have multiple `Store` objects to work with this way) and return a `StoreHandle`
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to the Ruby code (which is a UUID underneath).
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Also, the Ruby code never actually touches a `FileLockEntry` - it only gets a
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Handle for each `FileLockEntry` - which is a tuple of the `StoreHandle` and the
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`libimagstore::storeid::StoreId` for the Entry.
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Each operation on a `FileLockEntry` is then wrapped by this very library. Each
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time `FileLockEntry` is touched, this library fetches the appropriate `Store`
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object from the static `Cache`, then fetches the `FileLockEntry` object from it,
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does the operation and then drops the object (which implies that the actual
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`FileLockEntry` is `update()`d!).
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### The Hell?
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Yes, I know this is a lot of overhead. But what are we talking about here? This
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is Ruby code we're talking about here, so speed is not our concern.
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You could argue this is a hell of complexity introduced in this library and yes
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it is.
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If there are bugs (and I bet there are) they would be complex as hell.
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But that's it... if you have a better approach, please file a PR.
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## Tests?
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We have tests Ruby scripts in `./test`, they are not executed by travis-ci, as
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we need Ruby `2.3.0` for this and travis has `2.2.0` as latest version.
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But I hope we get it in travis soonish.
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## Ruby gem?
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This crate will contain both the Rust bindings for imag using `ruru` and a bunch
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of wrapper code for the actual `imag` gem.
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### Why another layer of indirection?
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As "ruru" does not yet support modules (which is sad btw) we would end up with
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functions for all the things.
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E.G.: `imag_runtime_setup()` instead of `Imag::Runtime::setup()`
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I want to add a Ruby gem to wrap these things.
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So basically a piece of Ruby which uses the Rust code to build
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`imag` as a gem which then exports a fine module system.
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### The module system:
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```text
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Imag (Module)
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EntryContent (Class (inherits from String))
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EntryHeader (Class)
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FileLockEntryHandle (Class)
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StoreHandle (Class)
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StoreId (Class)
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```
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`libimagentrytag` and the other `libimagentry*` libraries will be pulled into
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this library to support more advanced operations with the `FileLockEntryHandle`
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type.
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