update wasmtime from from 14.0.4 to 18.0.2 and follow wasmtimes fuel API changes

Author: tessi

CHANGELOG.md

@@ -14,19 +14,24 @@ Types of changes
 - `Fixed` for any bug fixes.
 - `Security` in case of vulnerabilities.
 
-## unreleased
+## [0.9.0 - unreleased]
 
-put your changes here
+Wasmtime rewrote their fuel-related API and simplified it. To remain consistent with Wasmtime, we follow this change in this release. A Wasmex `Store` now only implements `set_fuel/2` and `get_fuel/1`. All other methods are removed with this release.
+
+The underlying implementation of the fuel system got rewritten as well. If you are using fuel in your app,
+please check your fuel consumption values.
 
 * Thanks to @RoyalIcing for helping us keeping our dependencies up to date for this release 💜
 
 ### Added
 
 * official support for Elixir 1.15 and 1.16
+* fuel-related API got rewritten, because the underlying Wasm library (wasmtime) changed their API and we want to be consistent. Added `Store.get_fuel/1` and `Store.set_fuel/2` which is a much simpler API than before.
 
 ### Removed
 
 * removed support for Elixir 1.12
+* with the fuel-related API changed, the existing methods on `Store` (`consume_fuel`, `fuel_remaining`, `add_fuel`) were removed. Please call `set_fuel/2` and `get_fuel/1` instead.
 
 ### Changed
 

lib/wasmex/engine_config.ex

@@ -36,7 +36,7 @@ defmodule Wasmex.EngineConfig do
 
   Note that a `Wasmex.Store` starts with no fuel, so if you enable this option
   you'll have to be sure to pour some fuel into `Wasmex.Store` before
-  executing some code. See `Wasmex.StoreOrCaller.add_fuel/2`.
+  executing some code. See `Wasmex.StoreOrCaller.set_fuel/2`.
 
   ## Example
 

lib/wasmex/native.ex

@@ -69,9 +69,8 @@ defmodule Wasmex.Native do
   def store_new(_store_limits, _engine_resource), do: error()
   def store_new_wasi(_wasi_options, _store_limits, _engine_resource), do: error()
 
-  def store_or_caller_add_fuel(_store_or_caller_resource, _fuel), do: error()
-  def store_or_caller_consume_fuel(_store_or_caller_resource, _fuel), do: error()
-  def store_or_caller_fuel_consumed(_store_or_caller_resource), do: error()
+  def store_or_caller_get_fuel(_store_or_caller_resource), do: error()
+  def store_or_caller_set_fuel(_store_or_caller_resource, _fuel), do: error()
 
   # When the NIF is loaded, it will override functions in this module.
   # Calling error is handles the case when the nif could not be loaded.

lib/wasmex/store_or_caller.ex

@@ -32,7 +32,7 @@ defmodule Wasmex.StoreOrCaller do
   end
 
   @doc ~S"""
-  Adds fuel to this Store for Wasm to consume while executing.
+  Sets fuel to for Wasm to consume while executing.
 
   For this method to work, fuel consumption must be enabled via
   `Wasmex.EngineConfig.consume_fuel/2. By default a `Wasmex.Store`
@@ -58,100 +58,33 @@ defmodule Wasmex.StoreOrCaller do
 
       iex> {:ok, engine} = Wasmex.Engine.new(%Wasmex.EngineConfig{consume_fuel: true})
       iex> {:ok, store} = Wasmex.Store.new(nil, engine)
-      iex> Wasmex.StoreOrCaller.add_fuel(store, 10)
+      iex> Wasmex.StoreOrCaller.set_fuel(store, 10)
       :ok
   """
-  @spec add_fuel(__MODULE__.t(), pos_integer()) :: :ok | {:error, binary()}
-  def add_fuel(%__MODULE__{resource: resource}, fuel) do
-    case Wasmex.Native.store_or_caller_add_fuel(resource, fuel) do
+  @spec set_fuel(__MODULE__.t(), pos_integer()) :: :ok | {:error, binary()}
+  def set_fuel(%__MODULE__{resource: resource}, fuel) do
+    case Wasmex.Native.store_or_caller_set_fuel(resource, fuel) do
       {} -> :ok
       {:error, reason} -> {:error, reason}
     end
   end
 
-  @doc ~S"""
-  Synthetically consumes fuel from this Store.
-
-  For this method to work fuel, consumption must be enabled via
-  `Wasmex.EngineConfig.consume_fuel/2`.
-
-  WebAssembly execution will automatically consume fuel but if so desired
-  the embedder can also consume fuel manually to account for relative
-  costs of host functions, for example.
-
-  This function will attempt to consume `fuel` units of fuel from within
-  this store. If the remaining amount of fuel allows this then `{:ok, N}`
-  is returned where `N` is the amount of remaining fuel. Otherwise an
-  error is returned and no fuel is consumed.
-
-  ## Errors
-
-  This function will return an error either if fuel consumption is not
-  enabled via `Wasmex.EngineConfig.consume_fuel/2` or if `fuel` exceeds
-  the amount of remaining fuel within this store.
-
-  ## Examples
-
-      iex> {:ok, engine} = Wasmex.Engine.new(%Wasmex.EngineConfig{consume_fuel: true})
-      iex> {:ok, store} = Wasmex.Store.new(nil, engine)
-      iex> Wasmex.StoreOrCaller.add_fuel(store, 10)
-      iex> Wasmex.StoreOrCaller.fuel_remaining(store)
-      {:ok, 10}
-  """
-  @spec consume_fuel(__MODULE__.t(), pos_integer() | 0) ::
-          {:ok, pos_integer()} | {:error, binary()}
-  def consume_fuel(%__MODULE__{resource: resource}, fuel) do
-    case Wasmex.Native.store_or_caller_consume_fuel(resource, fuel) do
-      {:error, reason} -> {:error, reason}
-      fuel_remaining -> {:ok, fuel_remaining}
-    end
-  end
-
   @doc ~S"""
   Returns the amount of fuel available for future execution of this store.
 
   ## Examples
 
       iex> {:ok, engine} = Wasmex.Engine.new(%Wasmex.EngineConfig{consume_fuel: true})
       iex> {:ok, store} = Wasmex.Store.new(nil, engine)
-      iex> Wasmex.StoreOrCaller.add_fuel(store, 10)
-      iex> Wasmex.StoreOrCaller.fuel_remaining(store)
+      iex> Wasmex.StoreOrCaller.set_fuel(store, 10)
+      iex> Wasmex.StoreOrCaller.get_fuel(store)
       {:ok, 10}
   """
-  @spec fuel_remaining(__MODULE__.t()) :: {:ok, pos_integer()} | {:error, binary()}
-  def fuel_remaining(%__MODULE__{} = store_or_caller) do
-    consume_fuel(store_or_caller, 0)
-  end
-
-  @doc ~S"""
-  Returns the amount of fuel consumed by this store's execution so far.
-
-  Note that fuel, if enabled, must be initially added via
-  `Wasmex.StoreOrCaller.add_fuel/2`.
-
-  ## Errors
-
-  If fuel consumption is not enabled via
-  `Wasmex.EngineConfig.consume_fuel/2` then this function will return
-  an error tuple.
-
-  ## Examples
-
-      iex> {:ok, engine} = Wasmex.Engine.new(%Wasmex.EngineConfig{consume_fuel: true})
-      iex> {:ok, store} = Wasmex.Store.new(nil, engine)
-      iex> Wasmex.StoreOrCaller.fuel_consumed(store)
-      {:ok, 0}
-      iex> Wasmex.StoreOrCaller.add_fuel(store, 10)
-      iex> {:ok, _fuel} = Wasmex.StoreOrCaller.consume_fuel(store, 8)
-      iex> Wasmex.StoreOrCaller.fuel_consumed(store)
-      {:ok, 8}
-  """
-  @spec fuel_consumed(__MODULE__.t()) :: {:ok, pos_integer()} | {:error, binary()}
-  def fuel_consumed(%__MODULE__{resource: resource}) do
-    case Wasmex.Native.store_or_caller_fuel_consumed(resource) do
+  @spec get_fuel(__MODULE__.t()) :: {:ok, pos_integer()} | {:error, binary()}
+  def get_fuel(%__MODULE__{resource: resource}) do
+    case Wasmex.Native.store_or_caller_get_fuel(resource) do
       {:error, reason} -> {:error, reason}
-      nil -> {:error, "Could not consume fuel: fuel is not configured in this store"}
-      fuel_consumed -> {:ok, fuel_consumed}
+      get_fuel -> {:ok, get_fuel}
     end
   end
 end