Dynamic Thread Local Storage

Dynamic thread local storage is parlib’s way of providing pthread_key_create() and pthread_set/get_specific() style sematics for uthreads and vcores. Using dtls, different libraries can dynamically define their own set of dtls keys for thread local storage. Uthreads and vcores can then access the private regions associated with these keys through the API described below.

To access the dynamic thread local storage API, include the following header file:

#include <parlib/dtls.h>

Types

struct dtls_key;
typedef struct dtls_key dtls_key_t;
typedef void (*dtls_dtor_t)(void*);

struct dtls_key

dtls_key_t

A dynamic thread local storage key. Uthreads and vcores use these keys to gain access to their own thread local storage region associated with the key. Multiple keys can be created, with each key referring to a different set of thread local storage regions.

dtls_dtor_t

A function pointer defining a destructor function mapped to a specific dtls_key. Whenever a uthread has accessed a dtls_key that has a dtls_dtor_t mapped to it, the destructor function will be called before the uthread exits.

API Calls

dtls_key_t dtls_key_create(dtls_dtor_t dtor);
void dtls_key_delete(dtls_key_t key);
void set_dtls(dtls_key_t key, void *dtls);
void *get_dtls(dtls_key_t key);
void destroy_dtls();

dtls_key_t dtls_key_create(dtls_dtor_t dtor)

Initialize a dtls key for dynamically setting/getting thread local storage on a uthread or vcore. Takes a dtls_dtor_t as a paramameter and associates it with a new dtls_key_t, which gets returned.

void dtls_key_delete(dtls_key_t key)

Delete the provided dtls key.

void set_dtls(dtls_key_t key, void *dtls)

Associate a dtls storage region for the provided dtls key on the current uthread or vcore.

void *get_dtls(dtls_key_t key)

Get the dtls storage region previously assocaited with the provided dtls key on the current uthread or vcore. If no storage region has been associated yet, return NULL.

void destroy_dtls()

Destroy all dtls storage associated with all keys for the current uthread or vcore.