kcenon::thread::pool_policy Class Reference

Base interface for thread pool policies. More...

#include <pool_policy.h>

Inheritance diagram for kcenon::thread::pool_policy:

Collaboration diagram for kcenon::thread::pool_policy:

Public Member Functions
virtual	~pool_policy ()=default
	Virtual destructor for proper cleanup.
virtual auto	on_enqueue (job &j) -> common::VoidResult=0
	Called before a job is enqueued.
virtual void	on_job_start (job &j)=0
	Called when a worker starts executing a job.
virtual void	on_job_complete (job &j, bool success, const std::exception *error=nullptr)=0
	Called when a job completes (success or failure).
virtual auto	get_name () const -> std::string=0
	Gets the policy name for identification and logging.
virtual auto	is_enabled () const -> bool
	Checks if the policy is currently enabled.
virtual void	set_enabled (bool enabled)
	Enables or disables the policy.

Detailed Description

Base interface for thread pool policies.

Policies provide a way to extend thread pool behavior without modifying the thread_pool class itself. This follows the Strategy pattern and Single Responsibility Principle (SRP).

Design Principles

• Extensibility: New behaviors can be added by implementing this interface
• Composability: Multiple policies can be combined in a thread pool
• Non-intrusive: Policies don't require changes to core thread_pool code
• Testability: Each policy can be unit tested independently

Lifecycle Hooks

Policies receive callbacks at key points in the job lifecycle:

• on_enqueue(): Called before a job is added to the queue
• on_job_start(): Called when a worker begins executing a job
• on_job_complete(): Called when a job finishes (success or failure)

Thread Safety

All methods must be thread-safe as they may be called from multiple workers.

Usage Example

class my_logging_policy : public pool_policy {
public:
    auto on_enqueue(job& j) -> common::VoidResult override {
        LOG_INFO("Job {} enqueued", j.get_name());
        return common::ok();
    }
 
    void on_job_start(job& j) override {
        LOG_INFO("Job {} started", j.get_name());
    }
 
    void on_job_complete(job& j, bool success, const std::exception* error) override {
        LOG_INFO("Job {} completed: {}", j.get_name(), success ? "success" : "failed");
    }
 
    auto get_name() const -> std::string override { return "logging_policy"; }
};
 
pool->add_policy(std::make_unique<my_logging_policy>());

See also

circuit_breaker_policy

Definition at line 80 of file pool_policy.h.

Constructor & Destructor Documentation

~pool_policy()

virtual kcenon::thread::pool_policy::~pool_policy ( )

virtualdefault

Virtual destructor for proper cleanup.

Member Function Documentation

get_name()

virtual auto kcenon::thread::pool_policy::get_name ( ) const -> std::string

nodiscardpure virtual

Gets the policy name for identification and logging.

Returns

Policy name string.

Implemented in kcenon::thread::autoscaling_pool_policy, kcenon::thread::circuit_breaker_policy, and kcenon::thread::work_stealing_pool_policy.

is_enabled()

virtual auto kcenon::thread::pool_policy::is_enabled ( ) const -> bool

inlinenodiscardvirtual

Checks if the policy is currently enabled.

Returns

True if policy is active.

Reimplemented in kcenon::thread::autoscaling_pool_policy, kcenon::thread::circuit_breaker_policy, and kcenon::thread::work_stealing_pool_policy.

Definition at line 146 of file pool_policy.h.

{ return true; }

on_enqueue()

virtual auto kcenon::thread::pool_policy::on_enqueue ( job & j ) -> common::VoidResult

pure virtual

Called before a job is enqueued.

Parameters

j	Reference to the job being enqueued.

Returns

common::VoidResult - ok() to allow, error to reject the job.

Policies can use this to:

• Validate the job
• Apply transformations
• Reject jobs based on policy rules (e.g., circuit breaker open)

Thread Safety:

• Must be thread-safe
• Called from the enqueueing thread

Implemented in kcenon::thread::autoscaling_pool_policy, kcenon::thread::circuit_breaker_policy, and kcenon::thread::work_stealing_pool_policy.

on_job_complete()

virtual void kcenon::thread::pool_policy::on_job_complete ( job & j, bool success, const std::exception * error = nullptr )

pure virtual

Called when a job completes (success or failure).

Parameters

j	Reference to the completed job.
success	True if job completed successfully.
error	Pointer to exception if job failed, nullptr otherwise.

Policies can use this to:

• Record success/failure metrics
• Update circuit breaker state
• Log completion

Thread Safety:

• Must be thread-safe
• Called from the worker thread

Implemented in kcenon::thread::autoscaling_pool_policy, kcenon::thread::circuit_breaker_policy, and kcenon::thread::work_stealing_pool_policy.

on_job_start()

virtual void kcenon::thread::pool_policy::on_job_start ( job & j )

pure virtual

Called when a worker starts executing a job.

Parameters

j	Reference to the job being started.

Policies can use this to:

• Start timing
• Update metrics
• Log job start

Thread Safety:

• Must be thread-safe
• Called from the worker thread

Implemented in kcenon::thread::autoscaling_pool_policy, kcenon::thread::circuit_breaker_policy, and kcenon::thread::work_stealing_pool_policy.

set_enabled()

virtual void kcenon::thread::pool_policy::set_enabled ( bool enabled )

inlinevirtual

Enables or disables the policy.

Parameters

enabled

Whether to enable the policy.

Disabled policies have their hooks called but should no-op.

Reimplemented in kcenon::thread::autoscaling_pool_policy, kcenon::thread::circuit_breaker_policy, and kcenon::thread::work_stealing_pool_policy.

Definition at line 154 of file pool_policy.h.

{ (void)enabled; }

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The documentation for this class was generated from the following file:

• include/kcenon/thread/pool_policies/pool_policy.h