Convenience APIs

To make Cripts even more approachable, a set of optional convenience APIs are added to the core and top level name space. These APIs are not required to be used, and are enabled by adding a define to your Cript file (or when compiling the Cript). Making this addition optional allows users to choose whether they want to use these convenience APIs or stick with the traditional Cripts API style.

The convenience APIs carry a small (very small) overhead, due to how Cripts defers (or delays) initializations of objects until they are actually used. These new APIs are designed to be as efficient as possible, but they do introduce potential conflicts in the top level namespace. Here’s a simple example of how to enable these APIs:

#define CRIPTS_CONVENIENCE_APIS 1

#include <cripts/Preamble.hpp>

do_remap()
{
  urls.request.query.Keep({"foo", "bar"});
}

#include <cripts/Epilogue.hpp>

Note

The convenience APIs must be enabled before including the Preamble header. This define affects the entire compilation unit, so use it consistently throughout your Cript file.

Top level API additions

For the most common patterns, the top level API additions are client, server, and urls. These all have sub-level API additions, as explained in the following table:

Object	Traditional API equivalent
`client.request`	`borrow cripts::Client::Request::Get()`
`client.response`	`borrow cripts::Client::Response::Get()`
`client.connection`	`borrow cripts::Client::Connection::Get()`
`client.url`	`borrow cripts::Client::URL::Get()`
`server.request`	`borrow cripts::Server::Request::Get()`
`server.response`	`borrow cripts::Server::Response::Get()`
`server.connection`	`borrow cripts::Server::Connection::Get()`
`urls.request`	`borrow cripts::Client::URL::Get()`
`urls.pristine`	`borrow cripts::Pristine::URL::Get()`
`urls.cache`	`borrow cripts::Cache::URL::Get()`
`urls.parent`	`borrow cripts::Parent::URL::Get()`
`urls.remap.to`	`borrow cripts::Remap::To::URL::Get()`
`urls.remap.from`	`borrow cripts::Remap::From::URL::Get()`

The use of these top-level objects are identical to how you would use them with the traditional APIs. The following code shows both the traditional Cripts API and the new APIs in a simple example:

// Traditional Cripts API
do_remap()
{
  borrow req = cripts::Client::Request::Get();
  borrow url = cripts::Client::URL::Get();

  url.query.Keep({"foo", "bar"});
  req["X-Foo"] = "bar";
}

// Convenience API, does not need the borrow statements
do_remap()
{
  urls.request.query.Keep({"foo", "bar"});
  client.request["X-Foo"] = "bar";
}

Note

Both client.url and urls.request refer to the same underlying object, which is cripts::Client::URL. This means that any changes made to urls.request will also be reflected in client.url and vice versa.

Convenience macros

In addition to the top-level APIs, a set of convenience macros are provided as well, enabled with the same #define as above. The following macros have been added, which again populate the top level namespace:

Macro	Traditional API equivalent
`Regex(name, ...)`	`static cripts::Matcher::PCRE name(...)`
`ACL(name, ...)`	`static cripts::Matcher::Range::IP name(...)`
`StatusCode(code, ...)`	`cripts::Error::Status::Set(code, ...)`
`CreateCounter(id, name)`	`instance.metrics[id] = cripts::Metrics::Counter::Create(name)`
`CreateGauge(id, name)`	`instance.metrics[id] = cripts::Metrics::Gauge::Create(name)`
`FilePath(name, path)`	`static const cripts::File::Path name(path)`
`UniqueUUID()`	`cripts::UUID::Unique::Get()`
`TimeNow()`	`cripts::Time::Local::Now()`

These macros provide a more concise syntax for common operations. Here are some examples:

Regex and ACL Example

#define CRIPTS_CONVENIENCE_APIS 1
#include <cripts/Preamble.hpp>

do_remap()
{
  Regex(path_regex, "^/api/v([0-9]+)/(.*)$");
  ACL(internal_networks, {"192.168.0.0/16", "10.0.0.0/8", "172.16.0.0/12"});

  if (internal_networks.Match(client.connection.IP())) {
    if (path_regex.Match(urls.request.path)) {
      // Internal API access allowed
      client.request["X-API-Version"] = path_regex[1]; // First capture group
      client.request["X-API-Path"] = path_regex[2];    // Second capture group
    }
  } else {
    StatusCode(403, "Access denied");
  }
}

#include <cripts/Epilogue.hpp>

Metrics and File Example

#define CRIPTS_CONVENIENCE_APIS 1
#include <cripts/Preamble.hpp>

do_create_instance()
{
  CreateCounter(0, "requests.total");
  CreateGauge(1, "active.connections");
  FilePath(config_file, "/etc/ats/custom.conf");
}

do_remap()
{
  instance.metrics[0]->Increment(); // Increment request counter

  auto uuid = UniqueUUID();
  auto timestamp = TimeNow();

  client.request["X-Request-ID"] = uuid;
  client.request["X-Timestamp"] = timestamp.Epoch();
}

#include <cripts/Epilogue.hpp>

Performance Considerations

The convenience APIs are designed to have minimal overhead:

Lazy Initialization: Objects are only initialized when first accessed
Reference Semantics: The convenience objects are references to the same underlying objects
Compile-time Macros: Most convenience macros expand to the same code as traditional APIs

However, there are some considerations:

Namespace Pollution: The convenience APIs add names to the global namespace
Debugging: Stack traces may show convenience wrapper functions
Compatibility: Code using convenience APIs requires the #define to compile
Performance: While the overhead is minimal, it may not be suitable for performance-critical code due to the lazy initialization.

Best Practices

When using convenience APIs:

Consistent Usage: Either use convenience APIs throughout a Cript or stick to traditional APIs
Documentation: Comment when using convenience APIs for team clarity.
Testing: Test both with and without convenience APIs if maintaining compatibility.

Example of mixed usage (not recommended):

do_remap()
{
  // Mixed usage - avoid this pattern!
  borrow req = cripts::Client::Request::Get(); // Traditional
  urls.request.query.Keep({"foo"});            // Convenience
}

Better approach:

do_remap()
{
  // Consistent convenience API usage
  client.request["X-Processed"] = "true";
  urls.request.query.Keep({"foo", "bar"});
}

Note

The StatusCode macro currently only works with the status code, the reason message can not be set or overridden. Fixing this will require a future change in the Traffic Server code base.