Class: Schematic::RulesEngine

Inherits:
Object
  • Object
show all
Defined in:
lib/schematic/rules_engine.rb

Constant Summary collapse

WASM_PATH = 
File.join(__dir__, "wasm", "rulesengine.wasm")

Instance Method Summary collapse

Constructor Details

#initialize(logger: nil) ⇒ RulesEngine

Returns a new instance of RulesEngine.



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# File 'lib/schematic/rules_engine.rb', line 9

def initialize(logger: nil)
  @logger = logger || ConsoleLogger.new
  @initialized = false
  @mutex = Mutex.new
  @store = nil
  @memory = nil
  @alloc_fn = nil
  @dealloc_fn = nil
  @check_flag_fn = nil
  @set_time_fn = nil
  @get_result_json_fn = nil
  @get_result_json_length_fn = nil
  @get_version_key_fn = nil
end

Instance Method Details

#check_flag(flag, company = nil, user = nil) ⇒ Object 



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# File 'lib/schematic/rules_engine.rb', line 75

def check_flag(flag, company = nil, user = nil)
  raise "WASM rules engine not initialized" unless @initialized

  # Build combined JSON envelope (same format as Python/C#)
  envelope = { flag: strip_nulls(flag) }
  envelope[:company] = strip_nulls(company) if company
  envelope[:user] = strip_nulls(user) if user

  json_bytes = JSON.generate(envelope).encode("UTF-8")

  @mutex.synchronize do
    ptr = @alloc_fn.call(json_bytes.bytesize)
    begin
      @memory.write(ptr, json_bytes)

      # Supply the host's current time so the engine can compute
      # metric-period reset timestamps (SCHY-471). No-op on older wasm.
      @set_time_fn&.call((Time.now.to_f * 1000).to_i)

      result_len = @check_flag_fn.call(ptr, json_bytes.bytesize)

      raise "WASM checkFlagCombined returned error" if result_len.negative?

      result_ptr = @get_result_json_fn.call
      actual_len = @get_result_json_length_fn.call
      result_json = @memory.read(result_ptr, actual_len).force_encoding("UTF-8")

      normalize_keys(JSON.parse(result_json, symbolize_names: true))
    ensure
      @dealloc_fn.call(ptr, json_bytes.bytesize)
    end
  end
rescue StandardError => e
  @logger.error("WASM check_flag failed: #{e.message}")
  raise
end

#initialize! ⇒ Object 



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# File 'lib/schematic/rules_engine.rb', line 24

def initialize!
  @mutex.synchronize do
    return if @initialized

    unless File.exist?(WASM_PATH)
      @logger.warn("WASM binary not found at #{WASM_PATH}. Run scripts/download-wasm.sh to fetch it.")
      return
    end

    require "wasmtime"

    engine = Wasmtime::Engine.new
    mod = Wasmtime::Module.from_file(engine, WASM_PATH)

    linker = Wasmtime::Linker.new(engine)

    wasi_config = Wasmtime::WasiConfig.new
    wasi_config.set_stdin_string("")
    @store = Wasmtime::Store.new(engine, wasi_config: wasi_config)

    @instance = linker.instantiate(@store, mod)

    # Get raw WASM exports (C ABI — no wasm-bindgen)
    @memory = @instance.export("memory").to_memory
    @alloc_fn = export_func("alloc")
    @dealloc_fn = export_func("dealloc")
    @check_flag_fn = export_func("checkFlagCombined")
    # Optional: feed the wasm the current wall-clock time before each check.
    # The raw wasm32-unknown-unknown build has no clock under wasmtime
    # (SCHY-471); without this, metric-period reset timestamps are omitted.
    # Absent on older wasm — hence the safe-navigation call below.
    @set_time_fn = @instance.export("setCurrentTimeMillis")&.to_func
    @get_result_json_fn = export_func("getResultJson")
    @get_result_json_length_fn = export_func("getResultJsonLength")
    @get_version_key_fn = export_func("get_version_key_wasm")

    @initialized = true
    @logger.debug("WASM rules engine initialized")
  rescue LoadError => e
    @logger.warn("wasmtime gem not available, WASM rules engine disabled: #{e.message}")
    @initialized = false
  rescue StandardError => e
    @logger.error("Failed to initialize WASM rules engine: #{e.message}")
    @initialized = false
  end
end

#initialized? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/schematic/rules_engine.rb', line 71

def initialized?
  @initialized
end

#version_key ⇒ Object 



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# File 'lib/schematic/rules_engine.rb', line 112

def version_key
  raise "WASM rules engine not initialized" unless @initialized

  @mutex.synchronize do
    ptr = @get_version_key_fn.call
    # Read null-terminated string from WASM memory
    raw = @memory.read(ptr, 256)
    null_idx = raw.index("\0") || raw.bytesize
    raw[0, null_idx].force_encoding("UTF-8")
  end
end