Add scheduling, machine info, caching strategies and devices (#9)

Reviewed-on: Rubydragon/MetagraphOptimization.jl#9
Co-authored-by: Anton Reinhard <anton.reinhard@proton.me>
Co-committed-by: Anton Reinhard <anton.reinhard@proton.me>

src/devices/impl.jl

@@ -0,0 +1,52 @@
+"""
+    device_types()
+
+Return a vector of available and implemented device types.
+
+See also: [`DEVICE_TYPES`](@ref)
+"""
+function device_types()
+    return DEVICE_TYPES
+end
+
+"""
+    entry_device(machine::Machine)
+
+Return the "entry" device, i.e., the device that starts CPU threads and GPU kernels, and takes input values and returns the output value.
+"""
+function entry_device(machine::Machine)
+    return machine.devices[1]
+end
+
+"""
+    strategies(t::Type{T}) where {T <: AbstractDevice}
+
+Return a vector of available [`CacheStrategy`](@ref)s for the given [`AbstractDevice`](@ref).
+The caching strategies are used in code generation.
+"""
+function strategies(t::Type{T}) where {T <: AbstractDevice}
+    if !haskey(CACHE_STRATEGIES, t)
+        error("Trying to get strategies for $T, but it has no strategies defined!")
+    end
+
+    return CACHE_STRATEGIES[t]
+end
+
+"""
+    cache_strategy(device::AbstractDevice)
+
+Returns the cache strategy set for this device.
+"""
+function cache_strategy(device::AbstractDevice)
+    return device.cacheStrategy
+end
+
+"""
+    set_cache_strategy(device::AbstractDevice, cacheStrategy::CacheStrategy)
+
+Sets the device's cache strategy. After this call, [`cache_strategy`](@ref) should return `cacheStrategy` on the given device.
+"""
+function set_cache_strategy(device::AbstractDevice, cacheStrategy::CacheStrategy)
+    device.cacheStrategy = cacheStrategy
+    return nothing
+end