If a dead device comes back, put it into the right slot.

This fulfills one of the basic goals of hotplug, namely that a sound
card can disappear (ie., lost cable), be replugged and then safely
come back without any manual intervention.

diff --git a/alsa_input.cpp b/alsa_input.cpp
index cf9c69f4dd877213ba3d0230aba98fefdf7bbd62..78faaf31ffc1ee584cc4f3fccad7f7e5fd25f15c 100644 (file)
--- a/alsa_input.cpp
+++ b/alsa_input.cpp
@@ -450,16 +450,24 @@ ALSAPool::ProbeResult ALSAPool::probe_device_once(unsigned card_index, unsigned
        snd_ctl_card_info_alloca(&card_info);
        snd_ctl_card_info(ctl, card_info);
 
-       lock_guard<mutex> lock(mu);
-       unsigned internal_dev_index = find_free_device_index();
-       devices[internal_dev_index].address = address;
-       devices[internal_dev_index].name = snd_ctl_card_info_get_name(card_info);
-       devices[internal_dev_index].info = snd_pcm_info_get_name(pcm_info);
-       devices[internal_dev_index].num_channels = num_channels;
-       devices[internal_dev_index].state = Device::State::READY;
+       string name = snd_ctl_card_info_get_name(card_info);
+       string info = snd_pcm_info_get_name(pcm_info);
+
+       unsigned internal_dev_index;
+       {
+               lock_guard<mutex> lock(mu);
+               internal_dev_index = find_free_device_index(name, info, num_channels, address);
+               devices[internal_dev_index].address = address;
+               devices[internal_dev_index].name = name;
+               devices[internal_dev_index].info = info;
+               devices[internal_dev_index].num_channels = num_channels;
+               // Note: Purposefully does not overwrite held.
+       }
 
        fprintf(stderr, "%s: Probed successfully.\n", address);
 
+       reset_device(internal_dev_index);  // Restarts it if it is held (ie., we just replaced a dead card).
+
        return ALSAPool::ProbeResult::SUCCESS;
 }
 
@@ -570,16 +578,47 @@ void ALSAPool::set_card_state(unsigned index, ALSAPool::Device::State state)
                ;
 }
 
-unsigned ALSAPool::find_free_device_index()
+unsigned ALSAPool::find_free_device_index(const string &name, const string &info, unsigned num_channels, const string &address)
 {
+       // First try to find an exact match on a dead card.
+       for (unsigned i = 0; i < devices.size(); ++i) {
+               if (devices[i].state == Device::State::DEAD &&
+                   devices[i].address == address &&
+                   devices[i].name == name &&
+                   devices[i].info == info &&
+                   devices[i].num_channels == num_channels) {
+                       devices[i].state = Device::State::READY;
+                       return i;
+               }
+       }
+
+       // Then try to find a match on everything but the address
+       // (probably that devices were plugged back in a different order).
+       // If we have two cards that are equal, this might get them mixed up,
+       // but we don't have anything better.
+       for (unsigned i = 0; i < devices.size(); ++i) {
+               if (devices[i].state == Device::State::DEAD &&
+                   devices[i].name == name &&
+                   devices[i].info == info &&
+                   devices[i].num_channels == num_channels) {
+                       devices[i].state = Device::State::READY;
+                       return i;
+               }
+       }
+
+       // OK, so we didn't find a match; see if there are any empty slots.
        for (unsigned i = 0; i < devices.size(); ++i) {
                if (devices[i].state == Device::State::EMPTY) {
                        devices[i].state = Device::State::READY;
+                       devices[i].held = false;
                        return i;
                }
        }
+
+       // Failing that, we just insert the new device at the end.
        Device new_dev;
        new_dev.state = Device::State::READY;
+       new_dev.held = false;
        devices.push_back(new_dev);
        inputs.emplace_back(nullptr);
        return devices.size() - 1;

diff --git a/alsa_input.h b/alsa_input.h
index a93b984fb2ec48ff0d32d4fe4fcfa650317c2a04..4638e4bb802ff875dea5e48a59cb285fda852ff1 100644 (file)
--- a/alsa_input.h
+++ b/alsa_input.h
@@ -184,7 +184,10 @@ private:
 
        // Must be called with <mu> held. Will allocate a new entry if needed.
        // The returned entry will be set to READY state.
-       unsigned find_free_device_index();
+       unsigned find_free_device_index(const std::string &name,
+                                       const std::string &info,
+                                       unsigned num_channels,
+                                       const std::string &address);
 
        friend class ALSAInput;
 };