libzmq/src/mtrie.cpp
Pieter Hintjens f0f16505e5 Removed corporate advertisements from source file headers
Copyrights had become ads for Sustrik's corporate sponsors, going against the original
agreement to share copyrights with the community (that agreement was: one line stating
iMatix copyright + one reference to AUTHORS file). The proliferation of corporate ads
is also unfair to the many individual authors. I've removed ALL corporate title from
the source files so the copyright statements can now be centralized in AUTHORS and
source files can be properly updated on an annual basis.
2013-03-12 13:24:57 +01:00

432 lines
13 KiB
C++

/*
Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
This file is part of 0MQ.
0MQ is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
0MQ is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <new>
#include <algorithm>
#include "platform.hpp"
#if defined ZMQ_HAVE_WINDOWS
#include "windows.hpp"
#endif
#include "err.hpp"
#include "pipe.hpp"
#include "mtrie.hpp"
zmq::mtrie_t::mtrie_t () :
pipes (0),
min (0),
count (0),
live_nodes (0)
{
}
zmq::mtrie_t::~mtrie_t ()
{
if (pipes) {
delete pipes;
pipes = 0;
}
if (count == 1) {
zmq_assert (next.node);
delete next.node;
next.node = 0;
}
else
if (count > 1) {
for (unsigned short i = 0; i != count; ++i)
if (next.table [i])
delete next.table [i];
free (next.table);
}
}
bool zmq::mtrie_t::add (unsigned char *prefix_, size_t size_, pipe_t *pipe_)
{
return add_helper (prefix_, size_, pipe_);
}
bool zmq::mtrie_t::add_helper (unsigned char *prefix_, size_t size_,
pipe_t *pipe_)
{
// We are at the node corresponding to the prefix. We are done.
if (!size_) {
bool result = !pipes;
if (!pipes) {
pipes = new (std::nothrow) pipes_t;
alloc_assert (pipes);
}
pipes->insert (pipe_);
return result;
}
unsigned char c = *prefix_;
if (c < min || c >= min + count) {
// The character is out of range of currently handled
// charcters. We have to extend the table.
if (!count) {
min = c;
count = 1;
next.node = NULL;
}
else
if (count == 1) {
unsigned char oldc = min;
mtrie_t *oldp = next.node;
count = (min < c ? c - min : min - c) + 1;
next.table = (mtrie_t**)
malloc (sizeof (mtrie_t*) * count);
alloc_assert (next.table);
for (unsigned short i = 0; i != count; ++i)
next.table [i] = 0;
min = std::min (min, c);
next.table [oldc - min] = oldp;
}
else
if (min < c) {
// The new character is above the current character range.
unsigned short old_count = count;
count = c - min + 1;
next.table = (mtrie_t**) realloc (next.table,
sizeof (mtrie_t*) * count);
alloc_assert (next.table);
for (unsigned short i = old_count; i != count; i++)
next.table [i] = NULL;
}
else {
// The new character is below the current character range.
unsigned short old_count = count;
count = (min + old_count) - c;
next.table = (mtrie_t**) realloc (next.table,
sizeof (mtrie_t*) * count);
alloc_assert (next.table);
memmove (next.table + min - c, next.table,
old_count * sizeof (mtrie_t*));
for (unsigned short i = 0; i != min - c; i++)
next.table [i] = NULL;
min = c;
}
}
// If next node does not exist, create one.
if (count == 1) {
if (!next.node) {
next.node = new (std::nothrow) mtrie_t;
alloc_assert (next.node);
++live_nodes;
}
return next.node->add_helper (prefix_ + 1, size_ - 1, pipe_);
}
else {
if (!next.table [c - min]) {
next.table [c - min] = new (std::nothrow) mtrie_t;
alloc_assert (next.table [c - min]);
++live_nodes;
}
return next.table [c - min]->add_helper (prefix_ + 1, size_ - 1, pipe_);
}
}
void zmq::mtrie_t::rm (pipe_t *pipe_,
void (*func_) (unsigned char *data_, size_t size_, void *arg_),
void *arg_)
{
unsigned char *buff = NULL;
rm_helper (pipe_, &buff, 0, 0, func_, arg_);
free (buff);
}
void zmq::mtrie_t::rm_helper (pipe_t *pipe_, unsigned char **buff_,
size_t buffsize_, size_t maxbuffsize_,
void (*func_) (unsigned char *data_, size_t size_, void *arg_),
void *arg_)
{
// Remove the subscription from this node.
if (pipes && pipes->erase (pipe_) && pipes->empty ()) {
func_ (*buff_, buffsize_, arg_);
delete pipes;
pipes = 0;
}
// Adjust the buffer.
if (buffsize_ >= maxbuffsize_) {
maxbuffsize_ = buffsize_ + 256;
*buff_ = (unsigned char*) realloc (*buff_, maxbuffsize_);
alloc_assert (*buff_);
}
// If there are no subnodes in the trie, return.
if (count == 0)
return;
// If there's one subnode (optimisation).
if (count == 1) {
(*buff_) [buffsize_] = min;
buffsize_++;
next.node->rm_helper (pipe_, buff_, buffsize_, maxbuffsize_,
func_, arg_);
// Prune the node if it was made redundant by the removal
if (next.node->is_redundant ()) {
delete next.node;
next.node = 0;
count = 0;
--live_nodes;
zmq_assert (live_nodes == 0);
}
return;
}
// If there are multiple subnodes.
//
// New min non-null character in the node table after the removal
unsigned char new_min = min + count - 1;
// New max non-null character in the node table after the removal
unsigned char new_max = min;
for (unsigned short c = 0; c != count; c++) {
(*buff_) [buffsize_] = min + c;
if (next.table [c]) {
next.table [c]->rm_helper (pipe_, buff_, buffsize_ + 1,
maxbuffsize_, func_, arg_);
// Prune redundant nodes from the mtrie
if (next.table [c]->is_redundant ()) {
delete next.table [c];
next.table [c] = 0;
zmq_assert (live_nodes > 0);
--live_nodes;
}
else {
// The node is not redundant, so it's a candidate for being
// the new min/max node.
//
// We loop through the node array from left to right, so the
// first non-null, non-redundant node encountered is the new
// minimum index. Conversely, the last non-redundant, non-null
// node encountered is the new maximum index.
if (c + min < new_min)
new_min = c + min;
if (c + min > new_max)
new_max = c + min;
}
}
}
zmq_assert (count > 1);
// Free the node table if it's no longer used.
if (live_nodes == 0) {
free (next.table);
next.table = NULL;
count = 0;
}
// Compact the node table if possible
else
if (live_nodes == 1) {
// If there's only one live node in the table we can
// switch to using the more compact single-node
// representation
zmq_assert (new_min == new_max);
zmq_assert (new_min >= min && new_min < min + count);
mtrie_t *node = next.table [new_min - min];
zmq_assert (node);
free (next.table);
next.node = node;
count = 1;
min = new_min;
}
else
if (new_min > min || new_max < min + count - 1) {
zmq_assert (new_max - new_min + 1 > 1);
mtrie_t **old_table = next.table;
zmq_assert (new_min > min || new_max < min + count - 1);
zmq_assert (new_min >= min);
zmq_assert (new_max <= min + count - 1);
zmq_assert (new_max - new_min + 1 < count);
count = new_max - new_min + 1;
next.table = (mtrie_t**) malloc (sizeof (mtrie_t*) * count);
alloc_assert (next.table);
memmove (next.table, old_table + (new_min - min),
sizeof (mtrie_t*) * count);
free (old_table);
min = new_min;
}
}
bool zmq::mtrie_t::rm (unsigned char *prefix_, size_t size_, pipe_t *pipe_)
{
return rm_helper (prefix_, size_, pipe_);
}
bool zmq::mtrie_t::rm_helper (unsigned char *prefix_, size_t size_,
pipe_t *pipe_)
{
if (!size_) {
if (pipes) {
pipes_t::size_type erased = pipes->erase (pipe_);
zmq_assert (erased == 1);
if (pipes->empty ()) {
delete pipes;
pipes = 0;
}
}
return !pipes;
}
unsigned char c = *prefix_;
if (!count || c < min || c >= min + count)
return false;
mtrie_t *next_node =
count == 1 ? next.node : next.table [c - min];
if (!next_node)
return false;
bool ret = next_node->rm_helper (prefix_ + 1, size_ - 1, pipe_);
if (next_node->is_redundant ()) {
delete next_node;
zmq_assert (count > 0);
if (count == 1) {
next.node = 0;
count = 0;
--live_nodes;
zmq_assert (live_nodes == 0);
}
else {
next.table [c - min] = 0;
zmq_assert (live_nodes > 1);
--live_nodes;
// Compact the table if possible
if (live_nodes == 1) {
// If there's only one live node in the table we can
// switch to using the more compact single-node
// representation
unsigned short i;
for (i = 0; i < count; ++i)
if (next.table [i])
break;
zmq_assert (i < count);
min += i;
count = 1;
mtrie_t *oldp = next.table [i];
free (next.table);
next.node = oldp;
}
else
if (c == min) {
// We can compact the table "from the left"
unsigned short i;
for (i = 1; i < count; ++i)
if (next.table [i])
break;
zmq_assert (i < count);
min += i;
count -= i;
mtrie_t **old_table = next.table;
next.table = (mtrie_t**) malloc (sizeof (mtrie_t*) * count);
alloc_assert (next.table);
memmove (next.table, old_table + i, sizeof (mtrie_t*) * count);
free (old_table);
}
else
if (c == min + count - 1) {
// We can compact the table "from the right"
unsigned short i;
for (i = 1; i < count; ++i)
if (next.table [count - 1 - i])
break;
zmq_assert (i < count);
count -= i;
mtrie_t **old_table = next.table;
next.table = (mtrie_t**) malloc (sizeof (mtrie_t*) * count);
alloc_assert (next.table);
memmove (next.table, old_table, sizeof (mtrie_t*) * count);
free (old_table);
}
}
}
return ret;
}
void zmq::mtrie_t::match (unsigned char *data_, size_t size_,
void (*func_) (pipe_t *pipe_, void *arg_), void *arg_)
{
mtrie_t *current = this;
while (true) {
// Signal the pipes attached to this node.
if (current->pipes) {
for (pipes_t::iterator it = current->pipes->begin ();
it != current->pipes->end (); ++it)
func_ (*it, arg_);
}
// If we are at the end of the message, there's nothing more to match.
if (!size_)
break;
// If there are no subnodes in the trie, return.
if (current->count == 0)
break;
// If there's one subnode (optimisation).
if (current->count == 1) {
if (data_ [0] != current->min)
break;
current = current->next.node;
data_++;
size_--;
continue;
}
// If there are multiple subnodes.
if (data_ [0] < current->min || data_ [0] >=
current->min + current->count)
break;
if (!current->next.table [data_ [0] - current->min])
break;
current = current->next.table [data_ [0] - current->min];
data_++;
size_--;
}
}
bool zmq::mtrie_t::is_redundant () const
{
return !pipes && live_nodes == 0;
}