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Reaction API

The Reaction API provides functions and macros for use within reaction bodies, deadline violation handlers, and STP (Safe to Process) violation handlers. A pointer to the Environment is automatically available as env within reaction scope, enabling access to the environment API. Furthermore points to all effects, oberservers and sources are also made available.

reaction(t) {=
  instant_t now = env->get_logical_time(env);
=}

Time Query Functions

Query the current logical and physical time within the reactor system.

  • env->get_logical_time(env)

Returns the current logical time of the reactor system.

Returns: instant_t — Current logical time in nanoseconds

Example: 

instant_t now = env->get_logical_time(env);

  • env->get_elapsed_logical_time(env)

Returns the elapsed logical time since the program started.

Returns: instant_t — Elapsed logical time in nanoseconds

  • env->get_physical_time(env)

Returns the current physical (wall-clock) time.

Returns: instant_t — Current physical time in nanoseconds

  • env->get_elapsed_physical_time(env)

Returns the elapsed physical time since the program started.

Returns: instant_t — Elapsed physical time in nanoseconds

  • env->get_lag(env)

Returns the difference between logical and physical time (lag). A positive value indicates the system is keeping up with real-time.

Returns: interval_t — Lag in nanoseconds

Synchronization and Waiting

  • env->wait_for(env, duration)

Blocks the current reaction until the specified duration has elapsed.

Parameters: - duration: interval_t — Duration to wait in nanoseconds

Critical Sections

Protect shared resources in concurrent environments.

  • env->enter_critical_section(env)

Enters a critical section. No other reactions will execute until the critical section is left.

  • env->leave_critical_section(env)

Leaves the current critical section, allowing other reactions to execute.

Example: 

env->enter_critical_section(env);
// Protected code here
shared_resource++;
env->leave_critical_section(env);

Shutdown Control

  • env->request_shutdown(env)

Requests that the reactor system shut down gracefully after the current round of execution completes.

Port Operations

Read and write values on reactor ports.

  • lf_set(port, value)

Sets the value of an output port.

Parameters: - port: Output port handle - value: Value to set (type depends on port declaration)

Example: 

lf_set(output, 42);

  • lf_set_array(port, length, array)

Sets an array value on an output port.

Parameters: - port: Output port handle - length: Number of elements in the array - array: Pointer to the array data

Example: 

int values[] = {1, 2, 3};
lf_set_array(output, 3, values);

  • lf_get(port)

Reads the current value from an input port.

Returns: Current port value (type depends on port declaration)

Example: 

int value = lf_get(input);

  • lf_is_present(port)

Checks if a port has a value present at the current logical time.

Returns: bool — true if port is present, false otherwise

Example: 

if (lf_is_present(input)) {
  int value = lf_get(input);
}

Action Scheduling

Schedule logical actions to occur at a future logical time.

  • lf_schedule(action, delay)

Schedules an action to trigger after the specified delay.

Parameters: - action: Logical action handle - delay: interval_t — Delay in nanoseconds

Example: 

lf_schedule(my_action, MSEC(100)); // Schedule 100ms in the future

  • lf_schedule_array(action, delay, length, array)

Schedules an action with array payload to trigger after the specified delay.

Parameters: - action: Logical action handle - delay: interval_t — Delay in nanoseconds - length: Number of elements in the array - array: Pointer to the array data

Example: 

int data[] = {10, 20, 30};
lf_schedule_array(my_action, MSEC(50), 3, data);

Logging

Configure runtime logging to debug and monitor reactor execution. Verbosity is controlled via CMake compile definitions.

Log Levels

  • LF_LOG_LEVEL_OFF — Disable logging
  • LF_LOG_LEVEL_ERROR — Only errors
  • LF_LOG_LEVEL_WARN — Warnings and errors
  • LF_LOG_LEVEL_INFO — General information
  • LF_LOG_LEVEL_DEBUG — Detailed debug information

Global Log Configuration

Set logging level for all modules:

target_compile_definitions(reactor-uc PUBLIC LF_LOG_LEVEL_ALL=LF_LOG_LEVEL_DEBUG)

Per-Module Log Configuration

Set logging level for specific modules:

target_compile_definitions(reactor-uc PUBLIC LF_LOG_LEVEL_SCHED=LF_LOG_LEVEL_DEBUG)

Available Modules

  • LF_LOG_LEVEL_ENV — Environment
  • LF_LOG_LEVEL_SCHED — Scheduler
  • LF_LOG_LEVEL_QUEUE — Event queue
  • LF_LOG_LEVEL_FED — Federated execution
  • LF_LOG_LEVEL_TRIG — Triggers
  • LF_LOG_LEVEL_PLATFORM — Platform layer
  • LF_LOG_LEVEL_CONN — Connections
  • LF_LOG_LEVEL_NET — Network

Logging Features

Disable all logging: 

target_compile_definitions(reactor-uc PUBLIC LF_LOG_DISABLE)

Disable log colorization: 

target_compile_definitions(reactor-uc PUBLIC LF_COLORIZE_LOGS=0)

Disable log timestamps: 

target_compile_definitions(reactor-uc PUBLIC LF_TIMESTAMP_LOGS=0)

By default, logs are colorized and include timestamps.