Results for: "Data"

Computes the tangent of x (expressed in radians).

Domain: (-INFINITY, INFINITY)

Codomain: (-INFINITY, INFINITY)

Math.tan(0) #=> 0.0

Computes the hyperbolic tangent of x (expressed in radians).

Domain: (-INFINITY, INFINITY)

Codomain: (-1, 1)

Math.tanh(0) #=> 0.0

Waits for all children, returning an array of pid/status pairs (where status is a Process::Status object).

fork { sleep 0.2; exit 2 }   #=> 27432
fork { sleep 0.1; exit 1 }   #=> 27433
fork {            exit 0 }   #=> 27434
p Process.waitall

produces:

[[30982, #<Process::Status: pid 30982 exit 0>],
 [30979, #<Process::Status: pid 30979 exit 1>],
 [30976, #<Process::Status: pid 30976 exit 2>]]

Some operating systems retain the status of terminated child processes until the parent collects that status (normally using some variant of wait()). If the parent never collects this status, the child stays around as a zombie process. Process::detach prevents this by setting up a separate Ruby thread whose sole job is to reap the status of the process pid when it terminates. Use detach only when you do not intend to explicitly wait for the child to terminate.

The waiting thread returns the exit status of the detached process when it terminates, so you can use Thread#join to know the result. If specified pid is not a valid child process ID, the thread returns nil immediately.

The waiting thread has pid method which returns the pid.

In this first example, we don’t reap the first child process, so it appears as a zombie in the process status display.

p1 = fork { sleep 0.1 }
p2 = fork { sleep 0.2 }
Process.waitpid(p2)
sleep 2
system("ps -ho pid,state -p #{p1}")

produces:

27389 Z

In the next example, Process::detach is used to reap the child automatically.

p1 = fork { sleep 0.1 }
p2 = fork { sleep 0.2 }
Process.detach(p1)
Process.waitpid(p2)
sleep 2
system("ps -ho pid,state -p #{p1}")

(produces no output)

Detach the process from controlling terminal and run in the background as system daemon. Unless the argument nochdir is true (i.e. non false), it changes the current working directory to the root (“/”). Unless the argument noclose is true, daemon() will redirect standard input, standard output and standard error to /dev/null. Return zero on success, or raise one of Errno::*.

Add the –update-sources option

Raises a MissingAttributeError, NotAvailableValueError, MissingTagError or NotExpectedTagError if the element is not properly formatted.

Returns a Hash containing the following keys:

:accept

Number of started SSL/TLS handshakes in server mode

:accept_good

Number of established SSL/TLS sessions in server mode

:accept_renegotiate

Number of start renegotiations in server mode

:cache_full

Number of sessions that were removed due to cache overflow

:cache_hits

Number of successfully reused connections

:cache_misses

Number of sessions proposed by clients that were not found in the cache

:cache_num

Number of sessions in the internal session cache

:cb_hits

Number of sessions retrieved from the external cache in server mode

:connect

Number of started SSL/TLS handshakes in client mode

:connect_good

Number of established SSL/TLS sessions in client mode

:connect_renegotiate

Number of start renegotiations in client mode

:timeouts

Number of sessions proposed by clients that were found in the cache but had expired due to timeouts

Takes the first digit of the reply code to determine the status type

Like Enumerable#take, but chains operation to be lazy-evaluated.