Package 'synchronicity'

Attach to an existing mutex.

Description

Attach to an existing mutex using either a file or description object

Usage

attach.mutex(obj, ...)

## S4 method for signature 'character'
attach.mutex(obj, ...)

## S4 method for signature 'boost.mutex.descriptor'
attach.mutex(obj, ...)

Arguments

obj	the descriptor object.
...	other arguments needed by attach.

Value

A mutex.

---

Create a boost.mutex object

Description

This function creates a boost.mutex object.

Usage

boost.mutex(sharedName = NULL, timeout = NULL, create = TRUE)

Arguments

sharedName	The name of the shared resource corresponding to the mutex. By default a universal unique identifier is supplied.
timeout	The amount of time (in seconds) that the mutex should try to attempt to get a lock. By default no timeout is supplied and the mutex will attempt to acquire the lock indefinitely.
create	Should the mutex be created or are we attaching to an existing on. Default is TRUE.

Examples

# Create a boost.mutex object with default resource name and no timeout.
x = boost.mutex()
rm(x)
gc()

---

The boost.mutex class

Description

The boost.mutex class

---

An S4 class holding boost.mutex description information.

Description

Objects of class description allow users to “attach” to existing mutexes within or across processes.

Slots

description

the list of description information.

---

Describe the boost.mutex object

Description

The information required to “attach” to an existing mutex object.

Usage

## S4 method for signature 'boost.mutex'
describe(x)

Arguments

x	the boost mutex object to describe.

---

Accessor for descriptor objects

Description

Retrieve the list of description information from a descriptor object.

Usage

description(x)

## S4 method for signature 'descriptor'
description(x)

Arguments

x	the descriptor object.

Value

a list of description information.

---

An S4 class holding mutex description information.

Description

Objects of class description allow users to “attach” to existing mutexes within or across processes.

Slots

description

the list of description information.

---

Timeout operations for boost.mutex objects

Description

The is.timed function tells if a boost.mutex object has a timeout. The timeout function tells how long a mutex will wait for a timeout.

Usage

is.timed(m)

## S4 method for signature 'boost.mutex'
is.timed(m)

Arguments

m	a boost.mutex object to get timeout information for.

Value

is.timed returns TRUE if the object has a timeout and FALSE otherwise. If a timeout has been set timeout returns the number of seconds a boost.mutex object will attempt to acquire a lock and NULL otherwise.

Examples

x = boost.mutex(timeout=5)
y = boost.mutex()
print(is.timed(x))
print(is.timed(y))
print(timeout(x))
print(timeout(y))

---

Lock and Unlock a Mutex

Description

The lock and unlock functions allow a user to specify exclusive or shared access to a resource.

Usage

lock(m, ...)

lock.shared(m, ...)

unlock(m, ...)

unlock.shared(m, ...)

Arguments

m	a mutex.
...	options associated with the mutex being used including block which forces the mutex to return immediately after trying to acquire a lock.

Details

A call to lock gives exclusive access to a resource; no other mutex may acquire a lock. A call to to lock.shared allows other mutexes to acquire a shared lock on the resource. When shared lock is called while a exclusive lock has been acquired, the shared lock will block until the exclusive lock is release. Likewise, if an exclusive lock is called while a shared lock has been acquired, the exclusive lock will block until the shared lock is released.

Value

The function returns TRUE if the lock is successfully called and FALSE otherwise.

Examples

m = boost.mutex()
lock(m)
# Some code that needs to be synchronized...
unlock(m)

---

The boost.mutex class

Description

The boost.mutex class

---

Is it a shared mutex?

Description

Tells the user if a mutex is a shared mutex. If it is not then it must be a write (exclusive) mutex.

Usage

shared(m)

## S4 method for signature 'boost.mutex'
shared(m)

Arguments

m

the mutex

Value

TRUE if the mutex is shared, FALSE otherwise.

---

The name of a mutex's shared resource

Description

This function returns the shared resource associated with a boost.mutex object.

Usage

shared.name(m)

Arguments

m	a boost.mutex object

Value

A string specifying the shared resource associated with the given boost.mutex object.

Examples

x = boost.mutex()
print(shared.name(x))

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Create a universal unique identifier.

Description

This function creates an identifier that will be (with high probability) unique on a single machine or group of machines.

Usage

uuid()

Value

A unique string.

Examples

print(uuid())

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