session: add "terminate and reset" support for protocol stacks
[libsigrokdecode.git] / instance.c
index 6c54d8d16c83f62ce1db75b6b2653216ff394907..6fbdc01fe7e888c57b43e9ad2a3af6cd5dd2788a 100644 (file)
 
 extern SRD_PRIV GSList *sessions;
 
-/* module_sigrokdecode.c */
-extern SRD_PRIV PyObject *srd_logic_type;
+static void srd_inst_join_decode_thread(struct srd_decoder_inst *di);
+static void srd_inst_reset_state(struct srd_decoder_inst *di);
+SRD_PRIV void oldpins_array_seed(struct srd_decoder_inst *di);
+SRD_PRIV void oldpins_array_free(struct srd_decoder_inst *di);
 
 /** @endcond */
 
@@ -72,6 +74,7 @@ SRD_API int srd_inst_option_set(struct srd_decoder_inst *di,
        gint64 val_int;
        int ret;
        const char *val_str;
+       PyGILState_STATE gstate;
 
        if (!di) {
                srd_err("Invalid decoder instance.");
@@ -83,8 +86,11 @@ SRD_API int srd_inst_option_set(struct srd_decoder_inst *di,
                return SRD_ERR_ARG;
        }
 
+       gstate = PyGILState_Ensure();
+
        if (!PyObject_HasAttrString(di->decoder->py_dec, "options")) {
                /* Decoder has no options. */
+               PyGILState_Release(gstate);
                if (g_hash_table_size(options) == 0) {
                        /* No options provided. */
                        return SRD_OK;
@@ -166,6 +172,7 @@ err_out:
                srd_exception_catch("Stray exception in srd_inst_option_set()");
                ret = SRD_ERR_PYTHON;
        }
+       PyGILState_Release(gstate);
 
        return ret;
 }
@@ -249,14 +256,20 @@ SRD_API int srd_inst_channel_set_all(struct srd_decoder_inst *di,
                }
                pdch = sl->data;
                new_channelmap[pdch->order] = new_channelnum;
-               srd_dbg("Setting channel mapping: %s (index %d) = channel %d.",
+               srd_dbg("Setting channel mapping: %s (PD ch idx %d) = input data ch idx %d.",
                        pdch->id, pdch->order, new_channelnum);
        }
 
        srd_dbg("Final channel map:");
        num_required_channels = g_slist_length(di->decoder->channels);
        for (i = 0; i < di->dec_num_channels; i++) {
-               srd_dbg(" - index %d = channel %d (%s)", i, new_channelmap[i],
+               GSList *l = g_slist_nth(di->decoder->channels, i);
+               if (!l)
+                       l = g_slist_nth(di->decoder->opt_channels,
+                               i - num_required_channels);
+               pdch = l->data;
+               srd_dbg(" - PD ch idx %d (%s) = input data ch idx %d (%s)", i,
+                       pdch->id, new_channelmap[i],
                        (i < num_required_channels) ? "required" : "optional");
        }
 
@@ -296,6 +309,7 @@ SRD_API struct srd_decoder_inst *srd_inst_new(struct srd_session *sess,
        struct srd_decoder *dec;
        struct srd_decoder_inst *di;
        char *inst_id;
+       PyGILState_STATE gstate;
 
        i = 1;
        srd_dbg("Creating new %s instance.", decoder_id);
@@ -349,16 +363,24 @@ SRD_API struct srd_decoder_inst *srd_inst_new(struct srd_session *sess,
                di->channel_samples = g_malloc(di->dec_num_channels);
        }
 
+       /* Default to the initial pins being the same as in sample 0. */
+       oldpins_array_seed(di);
+
+       gstate = PyGILState_Ensure();
+
        /* Create a new instance of this decoder class. */
        if (!(di->py_inst = PyObject_CallObject(dec->py_dec, NULL))) {
                if (PyErr_Occurred())
                        srd_exception_catch("Failed to create %s instance",
                                        decoder_id);
+               PyGILState_Release(gstate);
                g_free(di->dec_channelmap);
                g_free(di);
                return NULL;
        }
 
+       PyGILState_Release(gstate);
+
        if (options && srd_inst_option_set(di, options) != SRD_OK) {
                g_free(di->dec_channelmap);
                g_free(di);
@@ -372,10 +394,20 @@ SRD_API struct srd_decoder_inst *srd_inst_new(struct srd_session *sess,
        di->inbuf = NULL;
        di->inbuflen = 0;
        di->abs_cur_samplenum = 0;
-       di->old_pins_array = NULL;
        di->thread_handle = NULL;
        di->got_new_samples = FALSE;
        di->handled_all_samples = FALSE;
+       di->want_wait_terminate = FALSE;
+
+       /*
+        * Strictly speaking initialization of statically allocated
+        * condition and mutex variables (or variables allocated on the
+        * stack) is not required, but won't harm either. Explicitly
+        * running init() will better match subsequent clear() calls.
+        */
+       g_cond_init(&di->got_new_samples_cond);
+       g_cond_init(&di->handled_all_samples_cond);
+       g_mutex_init(&di->data_mutex);
 
        /* Instance takes input from a frontend by default. */
        sess->di_list = g_slist_append(sess->di_list, di);
@@ -384,6 +416,66 @@ SRD_API struct srd_decoder_inst *srd_inst_new(struct srd_session *sess,
        return di;
 }
 
+static void srd_inst_join_decode_thread(struct srd_decoder_inst *di)
+{
+       if (!di)
+               return;
+       if (!di->thread_handle)
+               return;
+
+       srd_dbg("%s: Joining decoder thread.", di->inst_id);
+
+       /*
+        * Terminate potentially running threads which still
+        * execute the decoder instance's decode() method.
+        */
+       srd_dbg("%s: Raising want_term, sending got_new.", di->inst_id);
+       g_mutex_lock(&di->data_mutex);
+       di->want_wait_terminate = TRUE;
+       g_cond_signal(&di->got_new_samples_cond);
+       g_mutex_unlock(&di->data_mutex);
+
+       srd_dbg("%s: Running join().", di->inst_id);
+       (void)g_thread_join(di->thread_handle);
+       srd_dbg("%s: Call to join() done.", di->inst_id);
+       di->thread_handle = NULL;
+
+       /*
+        * Reset condition and mutex variables, such that next
+        * operations on them will find them in a clean state.
+        */
+       g_cond_clear(&di->got_new_samples_cond);
+       g_cond_init(&di->got_new_samples_cond);
+       g_cond_clear(&di->handled_all_samples_cond);
+       g_cond_init(&di->handled_all_samples_cond);
+       g_mutex_clear(&di->data_mutex);
+       g_mutex_init(&di->data_mutex);
+}
+
+static void srd_inst_reset_state(struct srd_decoder_inst *di)
+{
+       if (!di)
+               return;
+
+       srd_dbg("%s: Resetting decoder state.", di->inst_id);
+
+       /*
+        * Reset internal state of the decoder.
+        */
+       condition_list_free(di);
+       match_array_free(di);
+       di->abs_start_samplenum = 0;
+       di->abs_end_samplenum = 0;
+       di->inbuf = NULL;
+       di->inbuflen = 0;
+       di->abs_cur_samplenum = 0;
+       oldpins_array_free(di);
+       di->got_new_samples = FALSE;
+       di->handled_all_samples = FALSE;
+       di->want_wait_terminate = FALSE;
+       /* Conditions and mutex got reset after joining the thread. */
+}
+
 /**
  * Stack a decoder instance on top of another.
  *
@@ -399,7 +491,6 @@ SRD_API int srd_inst_stack(struct srd_session *sess,
                struct srd_decoder_inst *di_bottom,
                struct srd_decoder_inst *di_top)
 {
-
        if (session_is_valid(sess) != SRD_OK) {
                srd_err("Invalid session.");
                return SRD_ERR_ARG;
@@ -550,51 +641,83 @@ SRD_PRIV struct srd_decoder_inst *srd_inst_find_by_obj(const GSList *stack,
 /**
  * Set the list of initial (assumed) pin values.
  *
- * If the list already exists, do nothing.
- *
  * @param di Decoder instance to use. Must not be NULL.
+ * @param initial_pins A GArray of uint8_t values. Must not be NULL.
  *
- * @private
+ * @since 0.5.0
  */
-static void set_initial_pin_values(struct srd_decoder_inst *di)
+SRD_API int srd_inst_initial_pins_set_all(struct srd_decoder_inst *di, GArray *initial_pins)
 {
        int i;
        GString *s;
-       PyObject *py_initial_pins;
 
-       if (!di || !di->py_inst) {
+       if (!di) {
                srd_err("Invalid decoder instance.");
-               return;
-       }
-
-       /* Nothing to do if di->old_pins_array is already != NULL. */
-       if (di->old_pins_array) {
-               srd_dbg("Initial pins already set, nothing to do.");
-               return;
+               return SRD_ERR_ARG;
        }
 
-       /* Create an array of old (previous sample) pins, init to 0. */
-       di->old_pins_array = g_array_sized_new(FALSE, TRUE, sizeof(uint8_t), di->dec_num_channels);
-       g_array_set_size(di->old_pins_array, di->dec_num_channels);
+       if (!initial_pins)
+               return SRD_ERR_ARG;
 
-       /* Check if the decoder has set self.initial_pins. */
-       if (!PyObject_HasAttrString(di->py_inst, "initial_pins")) {
-               srd_dbg("Initial pins: all 0 (self.initial_pins not set).");
-               return;
+       if (initial_pins->len != (guint)di->dec_num_channels) {
+               srd_err("Incorrect number of channels (need %d, got %d).",
+                       di->dec_num_channels, initial_pins->len);
+               return SRD_ERR_ARG;
        }
 
-       /* Get self.initial_pins. */
-       py_initial_pins = PyObject_GetAttrString(di->py_inst, "initial_pins");
+       /* Sanity-check initial pin state values. */
+       for (i = 0; i < di->dec_num_channels; i++) {
+               if (initial_pins->data[i] <= 2)
+                       continue;
+               srd_err("Invalid initial channel %d pin state: %d.",
+                       i, initial_pins->data[i]);
+               return SRD_ERR_ARG;
+       }
 
-       /* Fill di->old_pins_array based on self.initial_pins. */
        s = g_string_sized_new(100);
+       oldpins_array_seed(di);
        for (i = 0; i < di->dec_num_channels; i++) {
-               di->old_pins_array->data[i] = PyLong_AsLong(PyList_GetItem(py_initial_pins, i));
+               di->old_pins_array->data[i] = initial_pins->data[i];
                g_string_append_printf(s, "%d, ", di->old_pins_array->data[i]);
        }
        s = g_string_truncate(s, s->len - 2);
        srd_dbg("Initial pins: %s.", s->str);
        g_string_free(s, TRUE);
+
+       return SRD_OK;
+}
+
+/** @private */
+SRD_PRIV void oldpins_array_seed(struct srd_decoder_inst *di)
+{
+       size_t count;
+       GArray *arr;
+
+       if (!di)
+               return;
+       if (di->old_pins_array)
+               return;
+
+       srd_dbg("%s: Seeding old pins, %s().", di->inst_id, __func__);
+       count = di->dec_num_channels;
+       arr = g_array_sized_new(FALSE, TRUE, sizeof(uint8_t), count);
+       g_array_set_size(arr, count);
+       memset(arr->data, SRD_INITIAL_PIN_SAME_AS_SAMPLE0, count);
+       di->old_pins_array = arr;
+}
+
+/** @private */
+SRD_PRIV void oldpins_array_free(struct srd_decoder_inst *di)
+{
+       if (!di)
+               return;
+       if (!di->old_pins_array)
+               return;
+
+       srd_dbg("%s: Releasing initial pin state.", di->inst_id);
+
+       g_array_free(di->old_pins_array, TRUE);
+       di->old_pins_array = NULL;
 }
 
 /** @private */
@@ -604,27 +727,30 @@ SRD_PRIV int srd_inst_start(struct srd_decoder_inst *di)
        GSList *l;
        struct srd_decoder_inst *next_di;
        int ret;
+       PyGILState_STATE gstate;
 
        srd_dbg("Calling start() method on protocol decoder instance %s.",
                        di->inst_id);
 
+       gstate = PyGILState_Ensure();
+
        /* Run self.start(). */
        if (!(py_res = PyObject_CallMethod(di->py_inst, "start", NULL))) {
                srd_exception_catch("Protocol decoder instance %s",
                                di->inst_id);
+               PyGILState_Release(gstate);
                return SRD_ERR_PYTHON;
        }
        Py_DecRef(py_res);
 
-       /* Set the initial pins based on self.initial_pins. */
-       set_initial_pin_values(di);
-
        /* Set self.samplenum to 0. */
        PyObject_SetAttrString(di->py_inst, "samplenum", PyLong_FromLong(0));
 
        /* Set self.matched to None. */
        PyObject_SetAttrString(di->py_inst, "matched", Py_None);
 
+       PyGILState_Release(gstate);
+
        /* Start all the PDs stacked on top of this one. */
        for (l = di->next_di; l; l = l->next) {
                next_di = l->data;
@@ -653,8 +779,7 @@ SRD_PRIV int srd_inst_start(struct srd_decoder_inst *di)
  */
 static gboolean sample_matches(uint8_t old_sample, uint8_t sample, struct srd_term *term)
 {
-       if (!term)
-               return FALSE;
+       /* Caller ensures term != NULL. */
 
        switch (term->type) {
        case SRD_TERM_HIGH:
@@ -694,6 +819,7 @@ static gboolean sample_matches(uint8_t old_sample, uint8_t sample, struct srd_te
        return FALSE;
 }
 
+/** @private */
 SRD_PRIV void match_array_free(struct srd_decoder_inst *di)
 {
        if (!di || !di->match_array)
@@ -703,6 +829,7 @@ SRD_PRIV void match_array_free(struct srd_decoder_inst *di)
        di->match_array = NULL;
 }
 
+/** @private */
 SRD_PRIV void condition_list_free(struct srd_decoder_inst *di)
 {
        GSList *l, *ll;
@@ -744,6 +871,7 @@ static void update_old_pins_array(struct srd_decoder_inst *di,
        if (!di || !di->dec_channelmap || !sample_pos)
                return;
 
+       oldpins_array_seed(di);
        for (i = 0; i < di->dec_num_channels; i++) {
                byte_offset = di->dec_channelmap[i] / 8;
                bit_offset = di->dec_channelmap[i] % 8;
@@ -752,25 +880,44 @@ static void update_old_pins_array(struct srd_decoder_inst *di,
        }
 }
 
+static void update_old_pins_array_initial_pins(struct srd_decoder_inst *di)
+{
+       uint8_t sample;
+       int i, byte_offset, bit_offset;
+       const uint8_t *sample_pos;
+
+       if (!di || !di->dec_channelmap)
+               return;
+
+       sample_pos = di->inbuf + ((di->abs_cur_samplenum - di->abs_start_samplenum) * di->data_unitsize);
+
+       oldpins_array_seed(di);
+       for (i = 0; i < di->dec_num_channels; i++) {
+               if (di->old_pins_array->data[i] != SRD_INITIAL_PIN_SAME_AS_SAMPLE0)
+                       continue;
+               byte_offset = di->dec_channelmap[i] / 8;
+               bit_offset = di->dec_channelmap[i] % 8;
+               sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
+               di->old_pins_array->data[i] = sample;
+       }
+}
+
 static gboolean term_matches(const struct srd_decoder_inst *di,
                struct srd_term *term, const uint8_t *sample_pos)
 {
        uint8_t old_sample, sample;
        int byte_offset, bit_offset, ch;
 
-       if (!di || !di->dec_channelmap || !term || !sample_pos)
-               return FALSE;
+       /* Caller ensures di, di->dec_channelmap, term, sample_pos != NULL. */
 
-       /* Overwritten below (or ignored for SRD_TERM_SKIP). */
-       old_sample = sample = 0;
+       if (term->type == SRD_TERM_SKIP)
+               return sample_matches(0, 0, term);
 
-       if (term->type != SRD_TERM_SKIP) {
-               ch = term->channel;
-               byte_offset = di->dec_channelmap[ch] / 8;
-               bit_offset = di->dec_channelmap[ch] % 8;
-               sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
-               old_sample = di->old_pins_array->data[ch];
-       }
+       ch = term->channel;
+       byte_offset = di->dec_channelmap[ch] / 8;
+       bit_offset = di->dec_channelmap[ch] % 8;
+       sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
+       old_sample = di->old_pins_array->data[ch];
 
        return sample_matches(old_sample, sample, term);
 }
@@ -781,8 +928,7 @@ static gboolean all_terms_match(const struct srd_decoder_inst *di,
        const GSList *l;
        struct srd_term *term;
 
-       if (!di || !cond || !sample_pos)
-               return FALSE;
+       /* Caller ensures di, cond, sample_pos != NULL. */
 
        for (l = cond; l; l = l->next) {
                term = l->data;
@@ -798,8 +944,7 @@ static gboolean at_least_one_condition_matched(
 {
        unsigned int i;
 
-       if (!di)
-               return FALSE;
+       /* Caller ensures di != NULL. */
 
        for (i = 0; i < num_conditions; i++) {
                if (di->match_array->data[i])
@@ -811,12 +956,13 @@ static gboolean at_least_one_condition_matched(
 
 static gboolean find_match(struct srd_decoder_inst *di)
 {
-       static uint64_t s = 0;
        uint64_t i, j, num_samples_to_process;
        GSList *l, *cond;
        const uint8_t *sample_pos;
        unsigned int num_conditions;
 
+       /* Caller ensures di != NULL. */
+
        /* Check whether the condition list is NULL/empty. */
        if (!di->condition_list) {
                srd_dbg("NULL/empty condition list, automatic match.");
@@ -836,7 +982,11 @@ static gboolean find_match(struct srd_decoder_inst *di)
        di->match_array = g_array_sized_new(FALSE, TRUE, sizeof(gboolean), num_conditions);
        g_array_set_size(di->match_array, num_conditions);
 
-       for (i = 0, s = 0; i < num_samples_to_process; i++, s++, (di->abs_cur_samplenum)++) {
+       /* Sample 0: Set di->old_pins_array for SRD_INITIAL_PIN_SAME_AS_SAMPLE0 pins. */
+       if (di->abs_cur_samplenum == 0)
+               update_old_pins_array_initial_pins(di);
+
+       for (i = 0; i < num_samples_to_process; i++, (di->abs_cur_samplenum)++) {
 
                sample_pos = di->inbuf + ((di->abs_cur_samplenum - di->abs_start_samplenum) * di->data_unitsize);
 
@@ -865,6 +1015,8 @@ static gboolean find_match(struct srd_decoder_inst *di)
  *
  * This function returns if there is an error, or when a match is found, or
  * when all samples have been processed (whether a match was found or not).
+ * This function immediately terminates when the decoder's wait() method
+ * invocation shall get terminated.
  *
  * @param di The decoder instance to use. Must not be NULL.
  * @param found_match Will be set to TRUE if at least one condition matched,
@@ -880,6 +1032,10 @@ SRD_PRIV int process_samples_until_condition_match(struct srd_decoder_inst *di,
        if (!di || !found_match)
                return SRD_ERR_ARG;
 
+       *found_match = FALSE;
+       if (di->want_wait_terminate)
+               return SRD_OK;
+
        /* Check if any of the current condition(s) match. */
        while (TRUE) {
                /* Feed the (next chunk of the) buffer to find_match(). */
@@ -916,20 +1072,81 @@ static gpointer di_thread(gpointer data)
 {
        PyObject *py_res;
        struct srd_decoder_inst *di;
+       int wanted_term;
+       PyGILState_STATE gstate;
 
        if (!data)
                return NULL;
 
        di = data;
 
-       /* Call self.decode(). Only returns if the PD throws an exception. */
+       srd_dbg("%s: Starting thread routine for decoder.", di->inst_id);
+
+       gstate = PyGILState_Ensure();
+
+       /*
+        * Call self.decode(). Only returns if the PD throws an exception.
+        * "Regular" termination of the decode() method is not expected.
+        */
        Py_IncRef(di->py_inst);
-       if (!(py_res = PyObject_CallMethod(di->py_inst, "decode", NULL))) {
+       srd_dbg("%s: Calling decode() method.", di->inst_id);
+       py_res = PyObject_CallMethod(di->py_inst, "decode", NULL);
+       srd_dbg("%s: decode() method terminated.", di->inst_id);
+
+       /*
+        * Make sure to unblock potentially pending srd_inst_decode()
+        * calls in application threads after the decode() method might
+        * have terminated, while it neither has processed sample data
+        * nor has terminated upon request. This happens e.g. when "need
+        * a samplerate to decode" exception is thrown.
+        */
+       g_mutex_lock(&di->data_mutex);
+       wanted_term = di->want_wait_terminate;
+       di->want_wait_terminate = TRUE;
+       di->handled_all_samples = TRUE;
+       g_cond_signal(&di->handled_all_samples_cond);
+       g_mutex_unlock(&di->data_mutex);
+
+       /*
+        * Check for the termination cause of the decode() method.
+        * Though this is mostly for information.
+        */
+       if (!py_res && wanted_term) {
+               /*
+                * Silently ignore errors upon return from decode() calls
+                * when termination was requested. Terminate the thread
+                * which executed this instance's decode() logic.
+                */
+               srd_dbg("%s: Thread done (!res, want_term).", di->inst_id);
+               PyErr_Clear();
+               PyGILState_Release(gstate);
+               return NULL;
+       }
+       if (!py_res) {
+               /*
+                * The decode() invocation terminated unexpectedly. Have
+                * the back trace printed, and terminate the thread which
+                * executed the decode() method.
+                */
+               srd_dbg("%s: decode() terminated unrequested.", di->inst_id);
                srd_exception_catch("Protocol decoder instance %s: ", di->inst_id);
-               exit(1); /* TODO: Proper shutdown. This is a hack. */
+               srd_dbg("%s: Thread done (!res, !want_term).", di->inst_id);
+               PyGILState_Release(gstate);
                return NULL;
        }
+
+       /*
+        * TODO: By design the decode() method is not supposed to terminate.
+        * Nevertheless we have the thread joined, and srd backend calls to
+        * decode() will re-start another thread transparently.
+        */
+       srd_dbg("%s: decode() terminated (req %d).", di->inst_id, wanted_term);
        Py_DecRef(py_res);
+       PyErr_Clear();
+
+       PyGILState_Release(gstate);
+
+       srd_dbg("%s: Thread done (with res).", di->inst_id);
 
        return NULL;
 }
@@ -988,10 +1205,6 @@ SRD_PRIV int srd_inst_decode(struct srd_decoder_inst *di,
                uint64_t abs_start_samplenum, uint64_t abs_end_samplenum,
                const uint8_t *inbuf, uint64_t inbuflen, uint64_t unitsize)
 {
-       PyObject *py_res;
-       srd_logic *logic;
-       long apiver;
-
        /* Return an error upon unusable input. */
        if (!di) {
                srd_dbg("empty decoder instance");
@@ -1012,7 +1225,9 @@ SRD_PRIV int srd_inst_decode(struct srd_decoder_inst *di,
 
        if (abs_start_samplenum != di->abs_cur_samplenum ||
            abs_end_samplenum < abs_start_samplenum) {
-               srd_dbg("incorrect sample numbers");
+               srd_dbg("Incorrect sample numbers: start=%" PRIu64 ", cur=%"
+                       PRIu64 ", end=%" PRIu64 ".", abs_start_samplenum,
+                       di->abs_cur_samplenum, abs_end_samplenum);
                return SRD_ERR_ARG;
        }
 
@@ -1024,56 +1239,96 @@ SRD_PRIV int srd_inst_decode(struct srd_decoder_inst *di,
                abs_end_samplenum - abs_start_samplenum, inbuflen, di->data_unitsize,
                di->inst_id);
 
-       apiver = srd_decoder_apiver(di->decoder);
+       /* If this is the first call, start the worker thread. */
+       if (!di->thread_handle) {
+               srd_dbg("No worker thread for this decoder stack "
+                       "exists yet, creating one: %s.", di->inst_id);
+               di->thread_handle = g_thread_new(di->inst_id,
+                                                di_thread, di);
+       }
 
-       if (apiver == 2) {
-               /*
-                * Create new srd_logic object. Each iteration around the PD's
-                * loop will fill one sample into this object.
-                */
-               logic = PyObject_New(srd_logic, (PyTypeObject *)srd_logic_type);
-               Py_INCREF(logic);
-               logic->di = (struct srd_decoder_inst *)di;
-               logic->abs_start_samplenum = abs_start_samplenum;
-               logic->itercnt = 0;
-               logic->inbuf = (uint8_t *)inbuf;
-               logic->inbuflen = inbuflen;
-               logic->sample = PyList_New(2);
-               Py_INCREF(logic->sample);
-
-               Py_IncRef(di->py_inst);
-               if (!(py_res = PyObject_CallMethod(di->py_inst, "decode",
-                       "KKO", abs_start_samplenum, abs_end_samplenum, logic))) {
-                       srd_exception_catch("Protocol decoder instance %s",
-                                       di->inst_id);
-                       return SRD_ERR_PYTHON;
-               }
-               di->abs_cur_samplenum = abs_end_samplenum;
-               Py_DecRef(py_res);
-       } else {
-               /* If this is the first call, start the worker thread. */
-               if (!di->thread_handle)
-                       di->thread_handle = g_thread_new("di_thread",
-                                                        di_thread, di);
-
-               /* Push the new sample chunk to the worker thread. */
-               g_mutex_lock(&di->data_mutex);
-               di->abs_start_samplenum = abs_start_samplenum;
-               di->abs_end_samplenum = abs_end_samplenum;
-               di->inbuf = inbuf;
-               di->inbuflen = inbuflen;
-               di->got_new_samples = TRUE;
-               di->handled_all_samples = FALSE;
-
-               /* Signal the thread that we have new data. */
-               g_cond_signal(&di->got_new_samples_cond);
-               g_mutex_unlock(&di->data_mutex);
-
-               /* When all samples in this chunk were handled, return. */
-               g_mutex_lock(&di->data_mutex);
-               while (!di->handled_all_samples)
-                       g_cond_wait(&di->handled_all_samples_cond, &di->data_mutex);
-               g_mutex_unlock(&di->data_mutex);
+       /* Push the new sample chunk to the worker thread. */
+       g_mutex_lock(&di->data_mutex);
+       di->abs_start_samplenum = abs_start_samplenum;
+       di->abs_end_samplenum = abs_end_samplenum;
+       di->inbuf = inbuf;
+       di->inbuflen = inbuflen;
+       di->got_new_samples = TRUE;
+       di->handled_all_samples = FALSE;
+       di->want_wait_terminate = FALSE;
+
+       /* Signal the thread that we have new data. */
+       g_cond_signal(&di->got_new_samples_cond);
+       g_mutex_unlock(&di->data_mutex);
+
+       /* When all samples in this chunk were handled, return. */
+       g_mutex_lock(&di->data_mutex);
+       while (!di->handled_all_samples && !di->want_wait_terminate)
+               g_cond_wait(&di->handled_all_samples_cond, &di->data_mutex);
+       g_mutex_unlock(&di->data_mutex);
+
+       return SRD_OK;
+}
+
+/**
+ * Terminate current decoder work, prepare for re-use on new input data.
+ *
+ * Terminates all decoder operations in the specified decoder instance
+ * and the instances stacked on top of it. Resets internal state such
+ * that the previously constructed stack can process new input data that
+ * is not related to previously processed input data. This avoids the
+ * expensive and complex re-construction of decoder stacks.
+ *
+ * Callers are expected to follow up with start, metadata, and decode
+ * calls like they would for newly constructed decoder stacks.
+ *
+ * @param di The decoder instance to call. Must not be NULL.
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ * @private
+ */
+SRD_PRIV int srd_inst_terminate_reset(struct srd_decoder_inst *di)
+{
+       PyGILState_STATE gstate;
+       PyObject *py_ret;
+       GSList *l;
+       int ret;
+
+       if (!di)
+               return SRD_ERR_ARG;
+
+       /*
+        * Request termination and wait for previously initiated
+        * background operation to finish. Reset internal state, but
+        * do not start releasing resources yet. This shall result in
+        * decoders' state just like after creation. This block handles
+        * the C language library side.
+        */
+       srd_dbg("Terminating instance %s", di->inst_id);
+       srd_inst_join_decode_thread(di);
+       srd_inst_reset_state(di);
+
+       /*
+        * Have the Python side's .reset() method executed (if the PD
+        * implements it). It's assumed that .reset() assigns variables
+        * very much like __init__() used to do in the past. Thus memory
+        * that was allocated in previous calls gets released by Python
+        * as it's not referenced any longer.
+        */
+       gstate = PyGILState_Ensure();
+       if (PyObject_HasAttrString(di->py_inst, "reset")) {
+               srd_dbg("Calling .reset() of instance %s", di->inst_id);
+               py_ret = PyObject_CallMethod(di->py_inst, "reset", NULL);
+               Py_XDECREF(py_ret);
+       }
+       PyGILState_Release(gstate);
+
+       /*
+        * Pass the "restart" request to all stacked decoders.
+        */
+       for (l = di->next_di; l; l = l->next) {
+               ret = srd_inst_terminate_reset(l->data);
+               if (ret != SRD_OK)
+                       return ret;
        }
 
        return SRD_OK;
@@ -1084,10 +1339,18 @@ SRD_PRIV void srd_inst_free(struct srd_decoder_inst *di)
 {
        GSList *l;
        struct srd_pd_output *pdo;
+       PyGILState_STATE gstate;
 
        srd_dbg("Freeing instance %s", di->inst_id);
 
+       srd_inst_join_decode_thread(di);
+
+       srd_inst_reset_state(di);
+
+       gstate = PyGILState_Ensure();
        Py_DecRef(di->py_inst);
+       PyGILState_Release(gstate);
+
        g_free(di->inst_id);
        g_free(di->dec_channelmap);
        g_free(di->channel_samples);