Class: NewRelic::Starter::Latch

Inherits:
Object
  • Object
show all
Defined in:
ext/new_relic_starter/new_relic_starter.c,
ext/new_relic_starter/new_relic_starter.c

Overview

NewRelic::Starter::Latch indicates whether the New Relic agent should be started.

Instance Method Summary collapse

Constructor Details

#NewRelic::Starter::Latch.new ⇒ Object #NewRelic::Starter::Latch.new(path) ⇒ Object

Returns a new NewRelic::Starter::Latch object.

The state of the latch is stored in memory mapped by mmap(2) and shared with a forked process.

If path is specified, the memory mapping is backed by the file and the state of the latch is shared with other latches backed by the same file.

NewRelic::Starter::Latch.new #=> #<NewRelic::Starter::Latch:0x00007fbecb04f038>
NewRelic::Starter::Latch.new("/path/to/latch") #=> #<NewRelic::Starter::Latch:0x00007fbec9808010>



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# File 'ext/new_relic_starter/new_relic_starter.c', line 90

static VALUE
latch_initialize(int argc, VALUE *argv, VALUE self)
{
    int fd = -1;
    void *addr;

    char *path = rb_check_arity(argc, 0, 1) ? RSTRING_PTR(argv[0]) : NULL;
    if (path != NULL) {
        fd = open_latch_file(path);
    }

    addr = mmap(NULL, 1, PROT_READ|PROT_WRITE, (fd == -1 ? MAP_ANONYMOUS|MAP_SHARED : MAP_SHARED), fd, 0);
    if (addr == MAP_FAILED) {
        int e = errno;
        close(fd);
        rb_raise(eError, "failed to create mapping for latch: %s", strerror(e));
    }
    close(fd);

    DATA_PTR(self) = addr;

    return self;
}

Instance Method Details

#open ⇒ nil

Opens the latch.

latch = NewRelic::Starter::Latch.new
latch.opened? #=> false
latch.open
latch.opened? #=> true

Returns:

  • (nil) 


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# File 'ext/new_relic_starter/new_relic_starter.c', line 131

static VALUE
latch_open(VALUE self)
{
    uint8_t *l = check_latch(self);
    *l = 1;
    return Qnil;
}

#opened? ⇒ Boolean

Returns true if the latch is opened.

latch = NewRelic::Starter::Latch.new
latch.opened? #=> false
latch.open
latch.opened? #=> true

Returns:

  • (Boolean) 


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# File 'ext/new_relic_starter/new_relic_starter.c', line 150

static VALUE
latch_opened(VALUE self)
{
    return *check_latch(self) == 1 ? Qtrue : Qfalse;
}