class ThreadGroup

ThreadGroup provides a means of keeping track of a number of threads as a group.

A given Thread object can only belong to one ThreadGroup at a time; adding a thread to a new group will remove it from any previous group.

Newly created threads belong to the same group as the thread from which they were created.

Constants

Default: The default ThreadGroup created when Ruby starts; all Threads belong to it by default.

Public Instance Methods

add(thread) → thgrp

Adds the given thread to this group, removing it from any other group to which it may have previously been a member.

puts "Initial group is #{ThreadGroup::Default.list}"
tg = ThreadGroup.new
t1 = Thread.new { sleep }
t2 = Thread.new { sleep }
puts "t1 is #{t1}"
puts "t2 is #{t2}"
tg.add(t1)
puts "Initial group now #{ThreadGroup::Default.list}"
puts "tg group now #{tg.list}"

This will produce:

Initial group is #<Thread:0x401bdf4c>
t1 is #<Thread:0x401b3c90>
t2 is #<Thread:0x401b3c18>
Initial group now #<Thread:0x401b3c18>#<Thread:0x401bdf4c>
tg group now #<Thread:0x401b3c90>

static VALUE
thgroup_add(VALUE group, VALUE thread)
{
    rb_thread_t *target_th = rb_thread_ptr(thread);
    struct thgroup *data;

    if (OBJ_FROZEN(group)) {
        rb_raise(rb_eThreadError, "can't move to the frozen thread group");
    }
    TypedData_Get_Struct(group, struct thgroup, &thgroup_data_type, data);
    if (data->enclosed) {
        rb_raise(rb_eThreadError, "can't move to the enclosed thread group");
    }

    if (OBJ_FROZEN(target_th->thgroup)) {
        rb_raise(rb_eThreadError, "can't move from the frozen thread group");
    }
    TypedData_Get_Struct(target_th->thgroup, struct thgroup, &thgroup_data_type, data);
    if (data->enclosed) {
        rb_raise(rb_eThreadError,
                 "can't move from the enclosed thread group");
    }

    target_th->thgroup = group;
    return group;
}

enclose → thgrp

Prevents threads from being added to or removed from the receiving ThreadGroup.

New threads can still be started in an enclosed ThreadGroup.

ThreadGroup::Default.enclose        #=> #<ThreadGroup:0x4029d914>
thr = Thread.new { Thread.stop }    #=> #<Thread:0x402a7210 sleep>
tg = ThreadGroup.new                #=> #<ThreadGroup:0x402752d4>
tg.add thr
#=> ThreadError: can't move from the enclosed thread group

static VALUE
thgroup_enclose(VALUE group)
{
    struct thgroup *data;

    TypedData_Get_Struct(group, struct thgroup, &thgroup_data_type, data);
    data->enclosed = 1;

    return group;
}

enclosed? → true or false

Returns true if the thgrp is enclosed. See also ThreadGroup#enclose.

static VALUE
thgroup_enclosed_p(VALUE group)
{
    struct thgroup *data;

    TypedData_Get_Struct(group, struct thgroup, &thgroup_data_type, data);
    return RBOOL(data->enclosed);
}

list → array

Returns an array of all existing Thread objects that belong to this group.

ThreadGroup::Default.list   #=> [#<Thread:0x401bdf4c run>]

static VALUE
thgroup_list(VALUE group)
{
    VALUE ary = rb_ary_new();
    rb_thread_t *th = 0;
    rb_ractor_t *r = GET_RACTOR();

    ccan_list_for_each(&r->threads.set, th, lt_node) {
        if (th->thgroup == group) {
            rb_ary_push(ary, th->self);
        }
    }
    return ary;
}