Android fd backed shm#79
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Use anonymous FDs for Android shared memory so clients can keep allocating and resizing buffers without relying on a device-visible shm directory.
Use typed allocator metadata for registered client buffers, remove unused fields, and stop checking in generated protobuf outputs while keeping Android fd-backed buffers shareable across publishers and subscribers.
Keep the Rust client aligned with the fd-backed buffer registration protocol so the full test suite builds again.
Anonymous memfds have no name, so the process-global registry only emulated shm_open-by-name for the unit test; the real Android client owns its descriptors in the BufferSet and shares them with subscribers via the server. Create now returns a caller-owned memfd, open-by-name is unsupported on Android, and destroy is a no-op there (no named object, no shadow file).
UDP discovery assumes peers can exchange datagrams directly and be reached on their advertised port, which fails across a NAT such as an Android emulator or VM. --tcp_discovery runs the Query/Advertise/Subscribe handshake over a single TCP connection that the peer with --peer_address dials (the other side listens), so only the NAT'd side needs to initiate and there is no source-port rewriting. --bridge_advertise_address lets a NAT'd server advertise a forwarded loopback endpoint for its bridge/retirement listeners and binds them to the any-address. Also: keep absl flag names on Android builds (ABSL_FLAGS_STRIP_NAMES=0) so server/tool command-line flags parse; add --local/--channel to the manual pub and --channel to sub; line-buffer their stdout; and add manual_tests/cross_host_bridge.sh which bridges a channel in both directions between two host servers or between the host and a running Android emulator. Verified both directions natively and on an arm64 emulator.
Add a README section covering UDP broadcast/unicast and the new TCP unicast discovery, the relevant server flags, --bridge_advertise_address, and the manual_tests/cross_host_bridge.sh cross-computer test. Link the Android guide.
The discovery connection list is an unordered collection keyed by connection identity with add/remove/iterate semantics, so a flat_hash_set of shared_ptr fits better than a vector (O(1) removal, no linear scan).
Key the registry by (session_id, buffer_index) and (slot_id, is_prefix) so register, find, and unregister are O(1) average instead of linear scans. Replace the ClientBuffers() vector accessor with ForEachClientBuffer() and NumClientBuffers().
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Removes the use of /dev/subspace for shared memory on android and uses memfd_create instead. This is sent to the server for safe keeping and for retrieval by other publishers and subscribers. This removes any mods needed for SELInux on Android.
Also adds Soong/Blueprint builds for Android and a Java client. Adds tests for Java client.
Adds
.cursor/skills/subspace-builds/SKILL.md, an agent-readable build guide. Agents should use it when asked to build, test, cross-compile, or debug Subspace builds across Bazel, CMake, Android, Soong/Blueprint, AOSP, QNX, Linux, or macOS.Cross-computer discovery and bridging across NAT
Adds an optional TCP unicast discovery mode so two servers can bridge channels even when they cannot exchange UDP datagrams directly (e.g. one runs inside a NAT'd VM or Android emulator). UDP broadcast/unicast discovery remains the default for the LAN case.
--tcp_discoveryruns theQuery/Advertise/Subscribehandshake over a single TCP connection. The server with--peer_addressdials the peer's--disc_port; the other listens. Because only the NAT'd side initiates, this avoids both the inbound-reachability and UDP source-port-rewrite problems. It also lets two servers run on one host without contending for the UDP discovery port.--bridge_advertise_address=IPmakes a NAT'd server advertise a forwarded loopback endpoint (e.g.127.0.0.1reached viaadb forward/adb reverse) for its bridge/retirement listeners, and binds those listeners to the any-address.Supporting changes:
ABSL_FLAGS_STRIP_NAMES=0in the bazel Android configs); without this the server/tools rejected every command-line flag (even--socket) on Android.manual_tests/pubgains--localand--channel;subgains--channel; both line-buffer stdout so scripted output isn't lost.manual_tests/cross_host_bridge.sh, a manual cross-computer test that bridges a channel in both directions and verifies delivery, in two modes:native— two servers on one host over loopback.emulator— this host bridged to a running Android emulator (sets up the adb tunnels automatically).Verified both directions natively and on an arm64 Android emulator (publish on Android/subscribe on host and vice versa). Documentation added to
README.md,docs/server-architecture.md, anddocs/android.md.