Acme-Parataxis

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lib/Acme/Parataxis.c  view on Meta::CPAN

 */
typedef struct {
    coro_handle_t context; /**< OS-specific context handle */

#ifndef _WIN32
    void * stack_p;  /**< Pointer to dynamically allocated fiber stack (Unix only) */
    size_t stack_sz; /**< Size of the allocated stack (Unix only) */
#endif

    /*
     * Perl Interpreter State Pointers.
     * These must be saved and restored during every context switch.
     */
    PERL_SI * si;            /**< Current Stack Info (tracks recursion and eval frames) */
    AV * curstack;           /**< The active Argument Stack (AV*) */
    SSize_t stack_sp_offset; /**< Stack Pointer offset from stack base */

    I32 * markstack;     /**< Base of the Mark Stack (tracks list start points) */
    I32 * markstack_ptr; /**< Current pointer into the Mark Stack */
    I32 * markstack_max; /**< Limit of the Mark Stack */

    I32 * scopestack;   /**< Base of the Scope Stack (tracks block nesting) */
    I32 scopestack_ix;  /**< Current index in the Scope Stack */
    I32 scopestack_max; /**< Limit of the Scope Stack */

    ANY * savestack;   /**< Base of the Save Stack (tracks local/my variables for cleanup) */
    I32 savestack_ix;  /**< Current index in the Save Stack */
    I32 savestack_max; /**< Limit of the Save Stack */

    SV ** tmps_stack; /**< Base of the Mortal Stack (tracks SVs needing refcnt decrement) */
    I32 tmps_ix;      /**< Current index in the Mortal Stack */
    I32 tmps_floor;   /**< Current floor of the Mortal Stack */
    I32 tmps_max;     /**< Limit of the Mortal Stack */

    JMPENV * top_env;   /**< Pointer to the top exception environment (eval/die buffers) */
    COP * curcop;       /**< Current Op Pointer (location in the source/bytecode) */
    OP * op;            /**< Current Operation being executed */
    PAD * comppad;      /**< Current lexical Pad (variable storage) */
    SV ** curpad;       /**< Array pointer to the current lexical Pad */
    PMOP * curpm;       /**< Current pattern match state */
    PMOP * curpm_under; /**< Current pattern match state under */
    PMOP * reg_curpm;   /**< Current regex match state */

    GV * defgv;      /**< The $_ global */
    GV * last_in_gv; /**< GV used in last <FH> */
    SV * rs;         /**< The $/ global */
    GV * ofsgv;      /**< The $, global */
    SV * ors_sv;     /**< The $\ global */
    GV * defoutgv;   /**< The default output filehandle */
    HV * curstash;   /**< Current package stash */
    HV * defstash;   /**< Default package stash */
    SV * errors;     /**< Outstanding queued errors */

    SV * user_cv;  /**< The Perl sub/coderef this fiber is running */
    SV * self_ref; /**< The Acme::Parataxis Perl object wrapper */

    SV * transfer_data; /**< Arguments or return values passed during yield/transfer */

    int id;          /**< Numeric ID of this fiber */
    int finished;    /**< Flag: 1 if the fiber has completed its entry_point */
    int parent_id;   /**< ID of the fiber that 'called' this one (asymmetric) */
    int last_sender; /**< ID of the fiber that last switched control to this one */
} para_fiber_t;

/** @name Job Status Constants */
///@{
#define JOB_FREE 0 /**< Slot is available for new tasks */
#define JOB_NEW 1  /**< Task is submitted but not yet picked up by a worker */
#define JOB_BUSY 2 /**< Task is currently being processed by a worker thread */
#define JOB_DONE 3 /**< Task has completed and results are ready */
///@}

/** @name Task Type Constants */
///@{
#define TASK_SLEEP 0   /**< Sleep for N milliseconds */
#define TASK_GET_CPU 1 /**< Retrieve current core ID */
#define TASK_READ 2    /**< Wait for read-readiness on a file descriptor */
#define TASK_WRITE 3   /**< Wait for write-readiness on a file descriptor */
///@}

/**
 * @union value_t
 * @brief Generic container for task input/output data.
 */
typedef union {
    int64_t i; /**< Integer/Pointer storage */
    double d;  /**< Floating point storage */
    char * s;  /**< String storage */
} value_t;

/**
 * @struct job_t
 * @brief Represents a task in the background thread pool queue.
 */
typedef struct {
    int fiber_id;      /**< ID of the Fiber that submitted this task */
    int target_thread; /**< Index of the assigned worker thread */
    int type;          /**< Type of task to perform (TASK_*) */
    value_t input;     /**< Input data for the task */
    value_t output;    /**< Result data populated by the worker */
    int timeout_ms;    /**< Timeout duration for I/O tasks */
    int status;        /**< Current lifecycle state (JOB_*) */
} job_t;

// Global Registry and State

/** @brief Maximum number of concurrent fibers allowed */
#define MAX_FIBERS 1024
/** @brief Array of active fiber structures */
static para_fiber_t * fibers[MAX_FIBERS];
/** @brief The context representing the main Perl thread */
static para_fiber_t main_context;
/** @brief ID of the currently executing fiber (-1 for Main) */
static int current_fiber_id = -1;

/** @brief Size of the background job queue */
#define MAX_JOBS 1024
/** @brief Fixed-size array for background tasks */
static job_t job_slots[MAX_JOBS];
/** @brief Mutex protecting access to the job queue */
static para_mutex_t queue_lock;

lib/Acme/Parataxis.c  view on Meta::CPAN

    main_context.defoutgv = PL_defoutgv;
    main_context.curstash = PL_curstash;
    main_context.defstash = PL_defstash;
    main_context.errors = PL_errors;
    system_initialized = 1;
#ifdef _WIN32
    /* Convert the main thread into a fiber so it can be switched out */
    if (!main_fiber_handle) {
        main_fiber_handle = ConvertThreadToFiber(NULL);
        if (!main_fiber_handle) {
            if (GetLastError() == ERROR_ALREADY_FIBER)
                main_fiber_handle = GetCurrentFiber();
        }
    }
#endif
    init_threads();
    return 0;
}

/**
 * @brief Performs the low-level OS context switch.
 *
 * Saves the Perl state and then uses OS primitives (SwitchToFiber or
 * swapcontext) to change execution flow.
 *
 * @param target_id ID of the target fiber (-1 for Main).
 */
void perform_switch(int target_id) {
    dTHX;
    if (target_id == current_fiber_id)
        return;
    para_fiber_t * from = (current_fiber_id == -1) ? &main_context : fibers[current_fiber_id];
    para_fiber_t * to = (target_id == -1) ? &main_context : fibers[target_id];
    to->last_sender = current_fiber_id;
    current_fiber_id = target_id;
    swap_perl_state(from, to);
#ifdef _WIN32
    if (target_id == -1)
        SwitchToFiber(main_fiber_handle);
    else
        SwitchToFiber(to->context);
#else
    swapcontext(&from->context, &to->context);
#endif
}

/**
 * @brief Yields execution back to the caller or the main thread.
 *
 * Suspends the current fiber and returns a value to the context that
 * last resumed or called this fiber.
 *
 * @param ret_val The Perl SV to "return" to the caller.
 * @return SV* The value passed in when this fiber is eventually resumed.
 */
DLLEXPORT SV * coro_yield(SV * ret_val) {
    dTHX;
    if (current_fiber_id == -1)
        return &PL_sv_undef;
    para_fiber_t * self = fibers[current_fiber_id];
    int parent = self->parent_id;
    if (parent != -1 && (!fibers[parent] || fibers[parent]->finished))
        parent = self->last_sender;
    else if (parent == -1)
        parent = self->last_sender;
    if (parent >= 0 && (!fibers[parent] || fibers[parent]->finished))
        parent = -1;
    para_fiber_t * caller = (parent == -1) ? &main_context : fibers[parent];

    /* Pass return value to caller */
    if (caller->transfer_data != ret_val) {
        if (caller->transfer_data && caller->transfer_data != &PL_sv_undef)
            SvREFCNT_dec(caller->transfer_data);
        caller->transfer_data = ret_val;
        if (ret_val && ret_val != &PL_sv_undef)
            SvREFCNT_inc(ret_val);
    }

    perform_switch(parent);

    /* Retrieve value passed back during resume */
    SV * res = self->transfer_data;
    self->transfer_data = &PL_sv_undef;
    if (res && res != &PL_sv_undef)
        sv_2mortal(res);
    return res;
}

/**
 * @brief Entry point function for all new fibers.
 *
 * Sets up the Perl environment (ENTER/SAVETMPS), unpacks arguments,
 * calls the user coderef, handles results/errors, and manages the
 * fiber's completion lifecycle.
 *
 * @param c Pointer to the fiber context being started.
 */
static void entry_point(para_fiber_t * c) {
    dTHX;
    ENTER;
    SAVETMPS;
    dSP;
    PUSHMARK(SP);

    /* Unpack arguments passed during coro_call */
    if (c->transfer_data && SvROK(c->transfer_data) && SvTYPE(SvRV(c->transfer_data)) == SVt_PVAV) {
        AV * args = (AV *)SvRV(c->transfer_data);
        I32 len = av_top_index(args) + 1;
        for (I32 i = 0; i < len; i++) {
            SV ** svp = av_fetch(args, i, 0);
            if (svp)
                XPUSHs(*svp);
        }
    }
    PUTBACK;

    /* Execute the Perl sub */
    int count = call_sv(c->user_cv, G_SCALAR | G_EVAL);

    SPAGAIN;
    SV * ret_val = &PL_sv_undef;
    if (count == 1)
        ret_val = POPs;
    PUTBACK;

    c->finished = true;

    /* Cleanup transfer data and store result */
    if (c->transfer_data && c->transfer_data != &PL_sv_undef) {
        SvREFCNT_dec(c->transfer_data);
        c->transfer_data = &PL_sv_undef;
    }
    if (ret_val && ret_val != &PL_sv_undef) {
        SvREFCNT_inc(ret_val);
        c->transfer_data = ret_val;
    }

    /* Update the Perl-level Acme::Parataxis object */
    if (c->self_ref && SvROK(c->self_ref)) {

lib/Acme/Parataxis.c  view on Meta::CPAN

            XPUSHs(ERRSV);
            PUTBACK;
            call_method("set_error", G_DISCARD);
        }
        else {
            XPUSHs(ret_val);
            PUTBACK;
            call_method("set_result", G_DISCARD);
        }
        FREETMPS;
        LEAVE;
    }
    FREETMPS;
    LEAVE;

    /* Final yield back to caller */
    coro_yield(c->transfer_data ? c->transfer_data : &PL_sv_undef);

    /* Loop indefinitely if resumed after finish */
    while (1)
        coro_yield(&PL_sv_undef);
}

#ifdef _WIN32
/** @brief Windows fiber callback wrapper. */
static void WINAPI fiber_entry(void * param) { entry_point((para_fiber_t *)param); }
#else
/** @brief POSIX makecontext callback wrapper. */
static void posix_entry(int fiber_id) { entry_point(fibers[fiber_id]); }
#endif

/**
 * @brief Allocates and prepares a new Fiber context.
 *
 * @param user_code Coderef to execute in the fiber.
 * @param self_ref Acme::Parataxis object to notify on completion.
 * @return int Unique ID of the new fiber, or negative on error.
 */
DLLEXPORT int create_fiber(SV * user_code, SV * self_ref) {
    dTHX;
    int idx = -1;
    for (int i = 0; i < MAX_FIBERS; i++) {
        if (fibers[i] == NULL) {
            idx = i;
            break;
        }
    }
    if (idx == -1)
        return -2;
    para_fiber_t * c = (para_fiber_t *)malloc(sizeof(para_fiber_t));
    if (!c)
        return -3;
    memset(c, 0, sizeof(para_fiber_t));
    c->user_cv = user_code;
    if (user_code && user_code != &PL_sv_undef)
        SvREFCNT_inc(user_code);
    c->self_ref = self_ref;
    if (self_ref && self_ref != &PL_sv_undef)
        SvREFCNT_inc(self_ref);
    c->id = idx;
    c->parent_id = -1;
    c->last_sender = -1;
    c->transfer_data = &PL_sv_undef;
    fibers[idx] = c;

    /* Initialize Perl stacks */
    init_perl_stacks(c);

#ifdef _WIN32
    c->context = CreateFiber(0, fiber_entry, c);
#else
    c->stack_sz = 512 * 1024;  // 512KB is plenty for Perl fibers
    if (posix_memalign(&c->stack_p, 16, c->stack_sz) != 0) {
        destroy_coro(idx);
        return -3;
    }
    getcontext(&c->context);
    c->context.uc_stack.ss_sp = c->stack_p;
    c->context.uc_stack.ss_size = c->stack_sz;
    c->context.uc_link = &main_context.context;
    makecontext(&c->context, (void (*)())posix_entry, 1, c->id);
#endif
    return idx;
}

/**
 * @brief Resumes a fiber (asymmetric call).
 *
 * Suspends the caller and switches execution to the specified fiber.
 * Sets the caller as the 'parent' for future yields.
 *
 * @param fiber_id Fiber ID to call.
 * @param args Perl SV (usually arrayref) to pass as arguments to the fiber.
 * @return SV* Result yielded by the fiber.
 */
DLLEXPORT SV * coro_call(int fiber_id, SV * args) {
    dTHX;
    if (fiber_id < 0 || fiber_id >= MAX_FIBERS || !fibers[fiber_id] || fibers[fiber_id]->finished)
        return &PL_sv_undef;
    if (fibers[fiber_id]->transfer_data != args) {
        if (fibers[fiber_id]->transfer_data && fibers[fiber_id]->transfer_data != &PL_sv_undef)
            SvREFCNT_dec(fibers[fiber_id]->transfer_data);
        fibers[fiber_id]->transfer_data = args;
        if (args && args != &PL_sv_undef)
            SvREFCNT_inc(args);
    }
    fibers[fiber_id]->parent_id = current_fiber_id;
    perform_switch(fiber_id);
    if (fibers[fiber_id] && fibers[fiber_id]->finished) {
        if (fibers[fiber_id]->transfer_data && fibers[fiber_id]->transfer_data != &PL_sv_undef) {
            SvREFCNT_dec(fibers[fiber_id]->transfer_data);
            fibers[fiber_id]->transfer_data = &PL_sv_undef;
        }
    }
    para_fiber_t * me = (current_fiber_id == -1) ? &main_context : fibers[current_fiber_id];
    SV * res = me->transfer_data;
    me->transfer_data = &PL_sv_undef;
    if (res && res != &PL_sv_undef)
        sv_2mortal(res);
    return res;
}

/**
 * @brief Transfers control directly to another fiber (symmetric).
 *
 * Suspends the current fiber and switches directly to the target. No
 * parent/child relationship is established.
 *
 * @param target_id Fiber ID to transfer to.
 * @param args Arguments to pass to the target.
 * @return SV* Data eventually transferred back to this fiber.
 */
DLLEXPORT SV * coro_transfer(int target_id, SV * args) {
    dTHX;
    if (target_id < -1 || (target_id >= 0 && (target_id >= MAX_FIBERS || !fibers[target_id])))
        return &PL_sv_undef;
    if (target_id >= 0 && fibers[target_id]->finished)
        return &PL_sv_undef;
    para_fiber_t * target = (target_id == -1) ? &main_context : fibers[target_id];
    if (target->transfer_data != args) {
        if (target->transfer_data && target->transfer_data != &PL_sv_undef)
            SvREFCNT_dec(target->transfer_data);
        target->transfer_data = args;
        if (args && args != &PL_sv_undef)
            SvREFCNT_inc(args);
    }
    perform_switch(target_id);
    if (target_id >= 0 && fibers[target_id] && fibers[target_id]->finished) {
        if (fibers[target_id]->transfer_data && fibers[target_id]->transfer_data != &PL_sv_undef) {
            SvREFCNT_dec(fibers[target_id]->transfer_data);
            fibers[target_id]->transfer_data = &PL_sv_undef;
        }
    }
    para_fiber_t * me = (current_fiber_id == -1) ? &main_context : fibers[current_fiber_id];
    SV * res = me->transfer_data;
    me->transfer_data = &PL_sv_undef;
    if (res && res != &PL_sv_undef)
        sv_2mortal(res);
    return res;
}

/** @brief Returns 1 if the fiber has finished execution. */
DLLEXPORT int is_finished(int fiber_id) {
    if (fiber_id < 0)
        return 0;
    return (fibers[fiber_id] && fibers[fiber_id]->finished) ? 1 : 0;
}

/** @brief Internal helper to reset subroutine depth for cleanup. */
static void recursive_depth_reset(pTHX_ CV * cv) {
    if (!cv || SvTYPE((SV *)cv) != SVt_PVCV)
        return;
    if (CvDEPTH(cv) > 0)
        CvDEPTH(cv) = 0;
}

/**
 * @brief Clears active pads in the fiber stack.
 *
 * Internal helper used during fiber destruction to ensure all active lexical
 * scopes are unwound and their variables freed.
 *
 * @param si The Stack Info structure of the fiber.
 */
static void _clear_pads_in_stack(pTHX_ PERL_SI * si) {
    if (!si || !si->si_cxstack)
        return;



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