--- /dev/null
+#ifndef _ALSA_POOL_H
+#define _ALSA_POOL_H 1
+
+#include <alsa/asoundlib.h>
+#include <atomic>
+#include <functional>
+#include <mutex>
+#include <string>
+#include <thread>
+#include <unordered_map>
+#include <vector>
+
+#include "alsa_input.h"
+#include "bmusb/bmusb.h"
+#include "timebase.h"
+
+class ALSAInput;
+class DeviceSpecProto;
+
+// The class dealing with the collective of all ALSA cards in the system.
+// In particular, it deals with enumeration of cards, and hotplug of new ones.
+class ALSAPool {
+public:
+ ~ALSAPool();
+
+ struct Device {
+ enum class State {
+ // There is no card here. (There probably used to be one,
+ // but it got removed.) We don't insert a card before
+ // we've actually probed it, ie., we know whether it
+ // can be captured from at all, and what its name is.
+ EMPTY,
+
+ // This card is ready for capture, as far as we know.
+ // (It could still be used by someone else; we don't know
+ // until we try to open it.)
+ READY,
+
+ // We are trying to start capture from this card, but we are not
+ // streaming yet. Note that this could in theory go on forever,
+ // if the card is in use by some other process; in the UI,
+ // we will show this state as “(busy)”.
+ STARTING,
+
+ // The card is capturing and sending data. If there's a fatal error,
+ // it could go back to STARTING, or it could go to DEAD
+ // (depending on the error).
+ RUNNING,
+
+ // The card is gone (e.g., unplugged). However, since there's
+ // still a bus using it, we can't just remove the entry.
+ // If the card comes back (ie., a new card is plugged in,
+ // and we believe it has the same configuration), it could be
+ // installed in place of this card, and then presumably be put
+ // back into STARTING or RUNNING.
+ DEAD
+ } state = State::EMPTY;
+
+ std::string address; // E.g. “hw:0,0”.
+ std::string name, info;
+ unsigned num_channels;
+ ALSAInput *input = nullptr; // nullptr iff EMPTY or DEAD.
+
+ // Whether the AudioMixer is interested in this card or not.
+ // “Interested” could mean either of two things: Either it is part of
+ // a bus mapping, or it is in the process of enumerating devices
+ // (to show to the user). A card that is _not_ held can disappear
+ // at any given time as a result of an error or hotplug event;
+ // a card that is held will go to the DEAD state instead.
+ bool held = false;
+
+ std::string display_name() const { return name + " (" + info + ")"; }
+ };
+
+ void init();
+
+ // Get the list of all current devices. Note that this will implicitly mark
+ // all of the returned devices as held, since the input mapping UI needs
+ // some kind of stability when the user is to choose. Thus, when you are done
+ // with the list and have set a new mapping, you must go through all the devices
+ // you don't want and release them using release_device().
+ std::vector<Device> get_devices();
+
+ void hold_device(unsigned index);
+ void release_device(unsigned index); // Note: index is allowed to go out of bounds.
+
+ // If device is held, start or restart capture. If device is not held,
+ // stop capture if it isn't already.
+ void reset_device(unsigned index);
+
+ // Note: The card must be held. Returns OUTPUT_FREQUENCY if the card is in EMPTY or DEAD.
+ unsigned get_capture_frequency(unsigned index);
+
+ // Note: The card must be held.
+ Device::State get_card_state(unsigned index);
+
+ // Only for ALSAInput.
+ void set_card_state(unsigned index, Device::State state);
+
+ // Just a short form for taking <mu> and then moving the card to
+ // EMPTY or DEAD state. Only for ALSAInput and for internal use.
+ void free_card(unsigned index);
+
+ // Create a new card, mark it immediately as DEAD and hold it.
+ // Returns the new index.
+ unsigned create_dead_card(const std::string &name, const std::string &info, unsigned num_channels);
+
+ // Make a protobuf representation of the given card, so that it can be
+ // matched against at a later stage. For AudioMixer only.
+ // The given card must be held.
+ void serialize_device(unsigned index, DeviceSpecProto *serialized);
+
+private:
+ mutable std::mutex mu;
+ std::vector<Device> devices; // Under mu.
+ std::vector<std::unique_ptr<ALSAInput>> inputs; // Under mu, corresponds 1:1 to devices.
+
+ // Keyed on device address (e.g. “hw:0,0”). If there's an entry here,
+ // it means we already have a thread doing retries, so we shouldn't
+ // start a new one.
+ std::unordered_map<std::string, unsigned> add_device_tries_left; // Under add_device_mutex.
+ std::mutex add_device_mutex;
+
+ static constexpr int num_retries = 10;
+
+ void inotify_thread_func();
+ void enumerate_devices();
+
+ // Try to add an input at the given card/device. If it succeeds, return
+ // synchronously. If not, fire off a background thread to try up to
+ // <num_retries> times.
+ void probe_device_with_retry(unsigned card_index, unsigned dev_index);
+ void probe_device_retry_thread_func(unsigned card_index, unsigned dev_index);
+
+ enum class ProbeResult {
+ SUCCESS,
+ DEFER,
+ FAILURE
+ };
+ ProbeResult probe_device_once(unsigned card_index, unsigned dev_index);
+
+ void unplug_device(unsigned card_index, unsigned dev_index);
+
+ // 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(const std::string &name,
+ const std::string &info,
+ unsigned num_channels,
+ const std::string &address);
+
+ friend class ALSAInput;
+};
+
+#endif // !defined(_ALSA_POOL_H)
projects / nageru / blobdiff