01-29-2009
poll() and select() returning guarantees that an attempted read will not block, it does not guarantee what will happen - error condition, EOF, whatever.
This is what POSIX says:
Quote:
A descriptor shall be considered ready for reading when a call to an input function with O_NONBLOCK clear would not block, whether or not the function would transfer data successfully. (The function might return data, an end-of-file indication, or an error other than one indicating that it is blocked, and in each of these cases the descriptor shall be considered ready for reading.)
Plus, there is no way to know how many bytes can be read if a read were successful.
Try just reading a single byte then poll() or select().
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queue(n) Tcl Data Structures queue(n)
NAME
queue - Create and manipulate queue objects
SYNOPSIS
package require Tcl 8.2
package require struct ?1.2.1?
queueName option ?arg arg ...?
queueName clear
queueName destroy
queueName get ?count?
queueName peek ?count?
queueName put item ?item ...?
queueName size
DESCRIPTION
The ::struct::queue command creates a new queue object with an associated global Tcl command whose name is queueName. This command may be
used to invoke various operations on the queue. It has the following general form:
queueName option ?arg arg ...?
Option and the args determine the exact behavior of the command. The following commands are possible for queue objects:
queueName clear
Remove all items from the queue.
queueName destroy
Destroy the queue, including its storage space and associated command.
queueName get ?count?
Return the front count items of the queue and remove them from the queue. If count is not specified, it defaults to 1. If count is
1, the result is a simple string; otherwise, it is a list. If specified, count must be greater than or equal to 1. If there are no
items in the queue, this command will return count empty strings.
queueName peek ?count?
Return the front count items of the queue, without removing them from the queue. If count is not specified, it defaults to 1. If
count is 1, the result is a simple string; otherwise, it is a list. If specified, count must be greater than or equal to 1. If
there are no items in the queue, this command will return count empty strings.
queueName put item ?item ...?
Put the item or items specified into the queue. If more than one item is given, they will be added in the order they are listed.
queueName size
Return the number of items in the queue.
KEYWORDS
stack, matrix, tree, graph
struct 1.2.1 queue(n)