WebServer Class Reference

A simulated web server that processes at most one request at a time. More...

#include <WebServer.h>

Public Member Functions
	WebServer (unsigned int id, unsigned long createdCycle=0)
	Creates an idle server.
unsigned int	id () const
bool	isIdle () const
bool	isRetiring () const
void	setRetiring (bool retiring)
	Marks or unmarks the server for retirement.
void	assign (const Request &request, unsigned long cycle)
	Starts processing a request.
bool	tick ()
	Advances the server by one clock cycle.
const std::optional< Request > &	current () const
const Request &	lastCompleted () const
unsigned int	remainingCycles () const
unsigned long	completedCount () const
unsigned long	busyCycles () const
unsigned long	createdCycle () const

Detailed Description

A simulated web server that processes at most one request at a time.

The LoadBalancer assigns a Request to an idle server. Every clock cycle the load balancer calls tick(), which consumes one cycle of the request's remaining work. When the remaining work reaches zero the server reports the completion and becomes idle again.

A server can be marked as retiring during a scale-down. A retiring server receives no new work; the load balancer removes it as soon as it is idle, so in-progress requests are never dropped.

Definition at line 26 of file WebServer.h.

Constructor & Destructor Documentation

WebServer()

WebServer::WebServer ( unsigned int id, unsigned long createdCycle = 0 )

explicit

Creates an idle server.

Parameters

id	Unique identifier shown in logs.
createdCycle	Clock cycle at which the server was brought online.

Definition at line 11 of file WebServer.cpp.

Member Function Documentation

id()

unsigned int WebServer::id

(

)

const

Returns

Unique server identifier.

Definition at line 14 of file WebServer.cpp.

isIdle()

bool WebServer::isIdle

(

)

const

Returns

True when the server has no request in progress.

Definition at line 18 of file WebServer.cpp.

isRetiring()

bool WebServer::isRetiring

(

)

const

Returns

True when the server is marked for removal after its current request.

Definition at line 22 of file WebServer.cpp.

setRetiring()

void WebServer::setRetiring

(

bool

retiring

)

Marks or unmarks the server for retirement.

Parameters

retiring

True to stop accepting new work; false to return it to service.

Definition at line 26 of file WebServer.cpp.

assign()

void WebServer::assign	(	const Request &	request,
		unsigned long	cycle )

Starts processing a request.

Work begins on the next tick(), so a request with taskCycles = 1 that is assigned at cycle t completes at cycle t + 1.

Parameters

request	Request to process; its taskCycles must be at least 1.
cycle	Clock cycle of the assignment, used for statistics.

Exceptions

std::logic_error

if the server is busy, retiring, or the task length is zero.

Definition at line 30 of file WebServer.cpp.

tick()

bool WebServer::tick

(

)

Advances the server by one clock cycle.

Returns

True if the current request finished during this cycle.

Definition at line 44 of file WebServer.cpp.

current()

const std::optional< Request > & WebServer::current

(

)

const

Returns

The request in progress, or an empty optional when idle.

Definition at line 59 of file WebServer.cpp.

lastCompleted()

const Request & WebServer::lastCompleted

(

)

const

Returns

The most recently completed request (valid after tick() returns true).

Definition at line 63 of file WebServer.cpp.

remainingCycles()

unsigned int WebServer::remainingCycles

(

)

const

Returns

Clock cycles of work left on the current request (0 when idle).

Definition at line 67 of file WebServer.cpp.

completedCount()

unsigned long WebServer::completedCount

(

)

const

Returns

Number of requests this server has completed.

Definition at line 71 of file WebServer.cpp.

busyCycles()

unsigned long WebServer::busyCycles

(

)

const

Returns

Number of clock cycles this server spent processing work.

Definition at line 75 of file WebServer.cpp.

createdCycle()

unsigned long WebServer::createdCycle

(

)

const

Returns

Clock cycle at which the server was created.

Definition at line 79 of file WebServer.cpp.

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

• WebServer.h
• WebServer.cpp