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[Feat] (Config, ConfigLoader): parse MOBILEGL_TRANSPORT and the MOBILEGL_IPC_* family entirely behind the disaggregated option, so the pull build's symbol set cannot move

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rereview
2026-09-11 13:05:05 -04:00
parent 41b4f8dfe3
commit ec20e7001d
2 changed files with 202 additions and 0 deletions
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MobileGL/Config.h
+99
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@@ -414,4 +414,103 @@ namespace MobileGL::MG_Config {
String PipeStatsFile;
};
extern FeaturesTable Features;
// ---------------------------------------------------------------------------------
// P5: the transport selector and the MOBILEGL_IPC_* family (ARCHITECTURE.md 16, 附 A)
// ---------------------------------------------------------------------------------
//
// MOBILEGL_TRANSPORT = monolith | inproc | spawn | unix:<path> | pipe:<name>.
//
// WHY `Transport` IS NOT A FeaturesTable MEMBER. ARCHITECTURE.md:580 requires that with
// MOBILEGL_BUILD_DISAGGREGATED=OFF it be a `constexpr Monolith`, so that the single hook
// in MG_Backend/Init.cpp compiles away entirely rather than becoming a branch nobody can
// take. A FeaturesTable member is a runtime field in every build, which is the opposite
// of that; it would also resize MG_Config::Features and break G1 (the pull build's
// symbol set must not move) for the same reason the MOBILEGL_PIPE_VERIFY knobs above sit
// behind their own #if.
//
// ONE CONSEQUENCE, STATED SO IT IS NOT REDISCOVERED: in a build without the option,
// MOBILEGL_TRANSPORT=inproc is ACCEPTED BY THE ENVIRONMENT AND SILENTLY IGNORED - the
// parser below does not exist to complain about it, and putting a complaint in the
// unconditional part of ConfigLoader would move a pull-build symbol. That is the exact
// shape of "the split lane ran monolith and went green", so the gate against it is a
// BUILD-level check, not a runtime one: `nm --defined-only libMobileGL.so | grep -i
// MG_Remote` must be non-empty in build-split (CONTRACT-P5.md table 3, and the CI job
// P5 adds beside build-linux-verify).
enum class TransportMode : Uint8 {
Monolith = 0, // today's in-library backend; no MG_Remote object is constructed
InProcess = 1, // P5: a real apply thread in this process, over the same G3 codec
Spawn = 2, // P6: fork/exec MobileGLServer, socketpair
UnixSocket = 3,// P6: connect to an existing AF_UNIX endpoint (Endpoint = <path>)
NamedPipe = 4, // P6: Windows named pipe (Endpoint = <name>)
};
#if MOBILEGL_BUILD_DISAGGREGATED
// Parsed once by MG_ConfigLoader::Init(). Defaults to Monolith even here: building the
// transport in is not the same as using it, and every existing lane of a build-split
// must keep running monolith unless it is asked for one.
extern TransportMode Transport;
// The <path> of `unix:` / the <name> of `pipe:`. Empty for the other three modes.
extern String TransportEndpoint;
// The MOBILEGL_IPC_* family. A separate table rather than more FeaturesTable members,
// for the G1 reason above and because every field here is meaningless without the
// transport: a build that cannot reach the MG_Remote code cannot honour one of them.
//
// P5 lands exactly the knobs P5's own packages read. A later phase's knob is added HERE,
// through the integrator, and not invented at its call site - ARCHITECTURE.md:615 holds
// the full planned inventory (PRESENT_CREDIT, POLL_ESCALATE, SHADOW_SHM,
// INLINE_PAYLOADS, TRACE, ATTACH, RESPAWN, IDLE_EXIT_S), and every one of those belongs
// to P6 or later.
struct IpcTable {
// MOBILEGL_IPC_SERVER_PATH: where to find libMobileGLServer. P6 consumes it; P5
// lands the parse because t1's ctest ENVIRONMENT blocks and add_trace_replay_test's
// SPLIT variant already carry it, and an environment variable that nothing parses is
// indistinguishable from one that is parsed and ignored.
String ServerPath;
// MOBILEGL_IPC_RING_MB: SEG_CMD size. A RECORD MAY BE AT MOST HALF OF THIS
// (RingProducer::MaxRecordBytes), so 8 MiB caps one record at 4 MiB; R-10 makes the
// codec publish a max-record-bytes counter rather than assume that is enough.
Uint32 RingMb = 8;
// MOBILEGL_IPC_STAGE_MB: SEG_STAGE size. Every blob and every var-tail's bytes live
// here (R-10: no chunking in P5, so nothing may exceed it).
Uint32 StageMb = 32;
// MOBILEGL_IPC_SPIN_US: spin before parking on a doorbell, either direction.
Uint32 SpinUs = 50;
// MOBILEGL_IPC_PERSISTENT_BLOCK_KB: block granularity of the persistent-map push.
// 0 IS A NEGATIVE CONTROL, NOT "unlimited": it disables the push, and
// PersistentCoherentMapScenario must go RED under it (exit gate E3(a)).
Uint32 PersistentBlockKb = 64;
// MOBILEGL_IPC_ADOPT_TIER: 2 = emulate (client keeps the shadow and pushes), which
// is the only tier P5 implements and the reason persistent-map-push can be non-zero
// at all (R-6). 0 and 1 parse and are Fatal at use with "P11"; they exist now so the
// negative control has a spelling the day P11 writes it.
Uint32 AdoptTier = 2;
// MOBILEGL_IPC_VERB_BARRIER: 1 = the client blocks at every verb boundary until
// appliedSeq reaches its emitSeq (R-1). 0 is the negative control: it is EXPECTED to
// be red, because 31 of the 63 PipeInputs fields are still pulled from a live
// GLContext by the client's residual fill and a free-running queue lets the server
// read a FUTURE value of them.
Uint32 VerbBarrier = 1;
// MOBILEGL_IPC_STRICT_ERRORS: promote a BARRIER-PULLED field read - and, in a split
// build, the seven sticky forwards that are otherwise exempt - from "count it in
// rsp" to Fatal (R-7.3).
Bool StrictErrors = false;
// MOBILEGL_IPC_AUDIT: after a record retires, the server fills the SEG_STAGE bytes
// it referenced with 0xDD (R-2.5). This is the ONLY mechanical control that an
// inproc implementation did not quietly keep using a pointer past its lifetime.
Bool Audit = false;
// MOBILEGL_IPC_SERVER_AFFINITY: `auto` (the default, big-core detection borrowed
// from ShaderCompilePool), `off`, or an explicit CPU mask. Kept as the raw string
// because the resolved mask is logged by whoever starts the apply thread, and the
// string is what an operator typed.
String ServerAffinity = "auto";
};
extern IpcTable Ipc;
#else
// The whole point: in a build without MG_Remote this folds at compile time, so
// `if (MG_Config::Transport != MG_Config::TransportMode::Monolith)` in Init.cpp is a
// discarded statement and the pull build gains no symbol, no branch and no byte.
inline constexpr TransportMode Transport = TransportMode::Monolith;
#endif
} // namespace MobileGL::MG_Config
MobileGL/ConfigLoader.cpp
+103
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@@ -25,6 +25,15 @@ namespace MobileGL::MG_Config {
// Zero/default-initialized at static-init time (all fields have constexpr-friendly
// defaults), so it is safe to read even if MG_ConfigLoader::Init has not run yet.
FeaturesTable Features;
#if MOBILEGL_BUILD_DISAGGREGATED
// Same contract, and for the same reason: MG_Backend::Init() reads Transport, and a
// build order that put it before MG_ConfigLoader::Init() must see Monolith rather than
// a torn enum. Defined only here - in a pull build Config.h makes Transport a constexpr
// and there is nothing to define.
TransportMode Transport = TransportMode::Monolith;
String TransportEndpoint;
IpcTable Ipc;
#endif
} // namespace MobileGL::MG_Config
namespace MobileGL::MG_ConfigLoader {
@@ -297,12 +306,106 @@ namespace MobileGL::MG_ConfigLoader {
#undef ENTRY
}
#if MOBILEGL_BUILD_DISAGGREGATED
// MOBILEGL_TRANSPORT = monolith | inproc | spawn | unix:<path> | pipe:<name>
// (ARCHITECTURE.md:583). Shaped after InitBackendType above: an exact-name table, then
// one fallback that names what it did instead. The two prefixed forms are the only
// reason this is not literally that function's ENTRY macro.
//
// spawn / unix: / pipe: PARSE AND THEN REFUSE. They are P6's, and the refusal is NAMED
// rather than silent, because the failure this avoids is a P6 lane that set
// MOBILEGL_TRANSPORT=spawn, fell back to monolith, and went green on the wrong arm.
// The mode is left at Monolith so nothing half-initializes.
inline void InitTransport() {
String value;
QueryEnvVariable("MOBILEGL_TRANSPORT", value, "monolith");
String lowered = value;
std::transform(lowered.begin(), lowered.end(), lowered.begin(),
[](unsigned char c) { return static_cast<char>(std::tolower(c)); });
MG_Config::TransportEndpoint.clear();
if (lowered.empty() || lowered == "monolith") {
MG_Config::Transport = MG_Config::TransportMode::Monolith;
return;
}
if (lowered == "inproc") {
MG_Config::Transport = MG_Config::TransportMode::InProcess;
MGLOG_I("Config: MOBILEGL_TRANSPORT=inproc - the MGPipe record stream crosses a real "
"ring to an apply thread");
return;
}
// The three P6 forms. Recognised precisely, so the diagnostic can say "not yet"
// rather than "unknown", which are different bugs on the operator's side.
if (lowered == "spawn" || lowered.compare(0, 5, "unix:") == 0 ||
lowered.compare(0, 5, "pipe:") == 0) {
MGLOG_E("Config: MOBILEGL_TRANSPORT='%s' names a transport P6 implements and P5 does "
"not; staying on monolith. This run is NOT a split run.",
value.c_str());
MG_Config::Transport = MG_Config::TransportMode::Monolith;
return;
}
MGLOG_W("Config: Ignoring invalid env variable MOBILEGL_TRANSPORT='%s'; expected "
"monolith|inproc|spawn|unix:<path>|pipe:<name>, using monolith",
value.c_str());
MG_Config::Transport = MG_Config::TransportMode::Monolith;
}
// The MOBILEGL_IPC_* family (Config.h IpcTable). Parsed unconditionally rather than only
// when Transport != Monolith: a knob that silently means nothing on one arm of an A/B is
// how an A/B stops being one, and the ranges below are the diagnostics.
inline void InitIpc() {
auto& ipc = MG_Config::Ipc;
QueryEnvVariable("MOBILEGL_IPC_SERVER_PATH", ipc.ServerPath, "");
// Both ring floors are 1 MiB, not 0: a ring caps ONE record at half its size, and
// the catalogue's largest fixed payload (MGPFramebufferState, 304 bytes) plus a
// create_shader_state archive already needs far more than a toy ring. The ceilings
// are sanity, not policy.
ipc.RingMb = QueryEnvUint32("MOBILEGL_IPC_RING_MB", 8, 1, 1024);
ipc.StageMb = QueryEnvUint32("MOBILEGL_IPC_STAGE_MB", 32, 1, 4096);
ipc.SpinUs = QueryEnvUint32("MOBILEGL_IPC_SPIN_US", 50, 0, 1000000);
// 0 is admitted ON PURPOSE and is the negative control of exit gate E3(a): it turns
// the persistent-map push OFF, and PersistentCoherentMapScenario must go red.
ipc.PersistentBlockKb = QueryEnvUint32("MOBILEGL_IPC_PERSISTENT_BLOCK_KB", 64, 0, 65536);
// 2 is the only tier P5 implements (R-6). 0 and 1 parse here and are refused at the
// point of use, which is where the "P11" in the message belongs.
ipc.AdoptTier = QueryEnvUint32("MOBILEGL_IPC_ADOPT_TIER", 2, 0, 2);
ipc.VerbBarrier = QueryEnvUint32("MOBILEGL_IPC_VERB_BARRIER", 1, 0, 1);
ipc.StrictErrors = QueryEnvFlag("MOBILEGL_IPC_STRICT_ERRORS");
ipc.Audit = QueryEnvFlag("MOBILEGL_IPC_AUDIT");
QueryEnvVariable("MOBILEGL_IPC_SERVER_AFFINITY", ipc.ServerAffinity, "auto");
if (MG_Config::Transport == MG_Config::TransportMode::Monolith) return;
// One line, on the arm where these numbers decide behaviour, because every one of
// them is a number a bug report has to quote.
MGLOG_I("Config: IPC ring=%uMiB stage=%uMiB spin=%uus persistent-block=%uKiB "
"adopt-tier=%u verb-barrier=%u strict=%d audit=%d affinity='%s'",
ipc.RingMb, ipc.StageMb, ipc.SpinUs, ipc.PersistentBlockKb, ipc.AdoptTier,
ipc.VerbBarrier, static_cast<int>(ipc.StrictErrors), static_cast<int>(ipc.Audit),
ipc.ServerAffinity.c_str());
if (ipc.VerbBarrier == 0) {
MGLOG_W("Config: MOBILEGL_IPC_VERB_BARRIER=0 is the R-1 NEGATIVE CONTROL and is "
"expected to fail: the client still pulls 31 of 63 PipeInputs fields from a "
"live GLContext, so an unbarriered queue lets the server read future values");
}
if (ipc.PersistentBlockKb == 0) {
MGLOG_W("Config: MOBILEGL_IPC_PERSISTENT_BLOCK_KB=0 is the E3(a) NEGATIVE CONTROL: "
"the persistent-map push is OFF and a coherent-map scenario must go red");
}
}
#endif
void Init() {
MGLOG_D("Loading configuration from environment variables...");
InitializeAcceptedEnvVariables();
InitBackendType();
InitFeatures();
#if MOBILEGL_BUILD_DISAGGREGATED
// After InitFeatures, so the one line InitIpc logs is the last word on this run's
// configuration, and before the accepted-env map is destroyed just below.
InitTransport();
InitIpc();
#endif
// Destroy the map since we won't need it anymore
acceptedEnvVariablesMap.reset();