R3

R3 is an URL router library with high performance, thus, it's implemented in C. It compiles your route paths into a prefix trie.

By using the prefix tree constructed in the start-up time, you can dispatch the path to the controller with high efficiency.

Requirement

Build Requirement

• autoconf
• automake
• check
• pkg-config

Runtime Requirement

• pcre
• (optional) graphviz version 2.38.0 (20140413.2041)
• (optional) libjson-c-dev

Pattern Syntax

/blog/post/{id}      use [^/]+ regular expression by default.
/blog/post/{id:\d+}  use `\d+` regular expression instead of default.

API

#include <r3/r3.h>

// create a router tree with 10 children capacity (this capacity can grow dynamically)
n = r3_tree_create(10);

int route_data = 3;

// insert the route path into the router tree
r3_tree_insert_path(n, "/bar", &route_data); // ignore the length of path

r3_tree_insert_pathl(n, "/zoo", strlen("/zoo"), &route_data );
r3_tree_insert_pathl(n, "/foo/bar", strlen("/foo/bar"), &route_data );

r3_tree_insert_pathl(n ,"/post/{id}", strlen("/post/{id}") , &route_data );

r3_tree_insert_pathl(n, "/user/{id:\\d+}", strlen("/user/{id:\\d+}"), &route_data );


// if you want to catch error, you may call the extended path function for insertion
int data = 10;
char *errstr = NULL;
node *ret = r3_tree_insert_pathl_ex(n, "/foo/{name:\\d{5}", strlen("/foo/{name:\\d{5}"), NULL, &data, &errstr);
if (ret == NULL) {
    // failed insertion
    printf("error: %s\n", errstr);
    free(errstr); // errstr is created from `asprintf`, so you have to free it manually.
}


// let's compile the tree!
char *errstr = NULL;
int err = r3_tree_compile(n, &errstr);
if (err != 0) {
    // fail
    printf("error: %s\n", errstr);
    free(errstr); // errstr is created from `asprintf`, so you have to free it manually.
}


// dump the compiled tree
r3_tree_dump(n, 0);

// match a route
node *matched_node = r3_tree_matchl(n, "/foo/bar", strlen("/foo/bar"), NULL);
if (matched_node) {
    int ret = *( (*int) matched_node->data );
}

// release the tree
r3_tree_free(n);

Capture Dynamic Variables

If you want to capture the variables from regular expression, you will need to create a match_entry object and pass the object to r3_tree_matchl function, the catched variables will be pushed into the match entry structure:

match_entry * entry = match_entry_create("/foo/bar");

// free the match entry
match_entry_free(entry);

And you can even specify the request method restriction:

entry->request_method = METHOD_GET;
entry->request_method = METHOD_POST;
entry->request_method = METHOD_GET | METHOD_POST;

When using match_entry, you may match the route with r3_tree_match_entry function:

node *matched_node = r3_tree_match_entry(n, entry);

Release Memroy

To release the memory, you may call r3_tree_free(node *tree) to release the whole tree structure, node*, edge*, route* objects that were inserted into the tree will be freed.

Routing with conditions

// create a router tree with 10 children capacity (this capacity can grow dynamically)
n = r3_tree_create(10);

int route_data = 3;

// insert the route path into the router tree
r3_tree_insert_routel(n, METHOD_GET | METHOD_POST, "/blog/post", sizeof("/blog/post") - 1, &route_data );

char *errstr = NULL;
int err = r3_tree_compile(n, &errstr);
if (err != 0) {
    // fail
    printf("error: %s\n", errstr);
    free(errstr); // errstr is created from `asprintf`, so you have to free it manually.
}


// in your http server handler

// create the match entry for capturing dynamic variables.
match_entry * entry = match_entry_create("/foo/bar");
entry->request_method = METHOD_GET;


route *matched_route = r3_tree_match_route(n, entry);
matched_route->data; // get the data from matched route

// free the objects at the end
r3_route_free(r1);
r3_tree_free(n);

Slug

A slug is a placeholder, which captures the string from the URL as a variable. Slugs will be compiled into regular expression patterns.

Slugs without patterns (like /user/{userId}) will be compiled into the [^/]+ pattern.

To specify the pattern of a slug, you may write a colon to separate the slug name and the pattern:

"/user/{userId:\\d+}"

The above route will use \d+ as its pattern.

Optimization

Simple regular expressions are optimized through a regexp pattern to opcode translator, which translates simple patterns into small & fast scanners.

By using this method, r3 reduces the matching overhead of pcre library.

Optimized patterns are: [a-z]+, [0-9]+, \d+, \w+, [^/]+ or [^-]+

Slugs without specified regular expression will be compiled into the [^/]+ pattern. therefore, it's optimized too.

Complex regular expressions will still use libpcre to match URL (partially).

Performance

The routing benchmark from stevegraham/rails' PR https://github.com/stevegraham/rails/pull/1:

             omg    10462.0 (±6.7%) i/s -      52417 in   5.030416s

And here is the result of the router journey:

             omg     9932.9 (±4.8%) i/s -      49873 in   5.033452s

r3 uses the same route path data for benchmarking, and here is the benchmark:

            3 runs, 5000000 iterations each run, finished in 1.308894 seconds
            11460057.83 i/sec

The Route Paths Of Benchmark

The route path generator is from https://github.com/stevegraham/rails/pull/1:

#!/usr/bin/env ruby
arr    = ["foo", "bar", "baz", "qux", "quux", "corge", "grault", "garply"]
paths  = arr.permutation(3).map { |a| "/#{a.join '/'}" }
paths.each do |path|
    puts "r3_tree_insert_path(n, \"#{path}\", NULL);"
end

Function prefix mapping

Function Prefix	Description
r3_tree_*	Tree related operations, which require a node to operate a whole tree
r3_node_*	Single node related operations, which do not go through its own children or parent.
r3_edge_*	Edge related operations
r3_route_*	Route related operations, which are needed only when the tree is defined by routes
match_entry_*	Match entry related operations, a match_entry is just like the request parameters

Rendering Routes With Graphviz

The r3_tree_render_file API let you render the whole route trie into a image.

To use graphviz, you need to enable graphviz while you run configure:

./configure --enable-graphviz

Here is the sample code of generating graph output:

node * n = r3_tree_create(1);

r3_tree_insert_path(n, "/foo/bar/baz",  NULL);
r3_tree_insert_path(n, "/foo/bar/qux",  NULL);
r3_tree_insert_path(n, "/foo/bar/quux",  NULL);
r3_tree_insert_path(n, "/foo/bar/corge",  NULL);
r3_tree_insert_path(n, "/foo/bar/grault",  NULL);
r3_tree_insert_path(n, "/garply/grault/foo",  NULL);
r3_tree_insert_path(n, "/garply/grault/bar",  NULL);
r3_tree_insert_path(n, "/user/{id}",  NULL);
r3_tree_insert_path(n, "/post/{title:\\w+}",  NULL);

char *errstr = NULL;
int err;
err = r3_tree_compile(n, &errstr);
if (err != 0) {
    // fail
    printf("error: %s\n", errstr);
    free(errstr); // errstr is created from `asprintf`, so you have to free it manually.
}

r3_tree_render_file(n, "png", "check_gvc.png");
r3_tree_free(n);

Or you can even export it with dot format:

digraph g {
	graph [bb="0,0,205.1,471"];
	node [label="\N"];
	"{root}"	 [height=0.5,
		pos="35.097,453",
		width=0.97491];
	"#1"	 [height=0.5,
		pos="35.097,366",
		width=0.75];
        ....

Graphviz Related Functions

int r3_tree_render_file(const node * tree, const char * format, const char * filename);

int r3_tree_render(const node * tree, const char *layout, const char * format, FILE *fp);

int r3_tree_render_dot(const node * tree, const char *layout, FILE *fp);

int r3_tree_render_file(const node * tree, const char * format, const char * filename);

JSON Output

You can render the whole tree structure into json format output.

Please run configure with the --enable-json option.

Here is the sample code to generate JSON string:

json_object * obj = r3_node_to_json_object(n);

const char *json = r3_node_to_json_pretty_string(n);
printf("Pretty JSON: %s\n",json);

const char *json = r3_node_to_json_string(n);
printf("JSON: %s\n",json);

Use case in PHP

not implemented yet

// Here is the paths data structure
$paths = [
    '/blog/post/{id}' => [ 'controller' => 'PostController' , 'action' => 'item'   , 'method'   => 'GET' ] , 
    '/blog/post'      => [ 'controller' => 'PostController' , 'action' => 'list'   , 'method'   => 'GET' ] , 
    '/blog/post'      => [ 'controller' => 'PostController' , 'action' => 'create' , 'method' => 'POST' ]  , 
    '/blog'           => [ 'controller' => 'BlogController' , 'action' => 'list'   , 'method'   => 'GET' ] , 
];
$rs = r3_compile($paths, 'persisten-table-id');
$ret = r3_dispatch($rs, '/blog/post/3' );
list($complete, $route, $variables) = $ret;

// matched conditions aren't done yet
list($error, $message) = r3_validate($route); // validate route conditions
if ( $error ) {
    echo $message; // "Method not allowed", "...";
}

Install

sudo apt-get install check libpcre3 libpcre3-dev libjemalloc-dev libjemalloc1 build-essential libtool automake autoconf pkg-config
sudo apt-get install graphviz-dev graphviz  # if you want graphviz
./autogen.sh
./configure && make
sudo make install

Run Unit Tests

./configure --enable-check
make check

Enable Graphviz

./configure --enable-graphviz

With jemalloc

./configure --with-malloc=jemalloc

Binding For Other Languages

• Perl Router::R3 by @CindyLinz https://metacpan.org/pod/Router::R3
• Python pyr3 by @lucemia https://github.com/lucemia/pyr3
• Python pyr3 by @thedrow https://github.com/thedrow/pyr3
• Haskell r3 by @MnO2 https://github.com/MnO2/r3

License

This software is released under MIT License.