memopt & bugfixes: Clean up session system while keeping init flexible

Everest now lives and dies like the other side of the moon to sys-init,
 in order to get rid of the session nonsense that nobody was using anyway.
While this means applications not using neoux will act slightly
 differently to applications that do, I don't think this will be a
 problem.

code/apps/sys-everest.lua

@@ -57,14 +57,14 @@ monitors[0] = {nil, nil, 160, 50}
 -- line y
 local surfaces = {}
 
+-- Stops the main loop
+local shuttingDown = false
+
 local savingThrow = neo.requestAccess("x.neo.sys.manage")
 if savingThrow then
  savingThrow.registerForShutdownEvent()
  savingThrow.registerSavingThrow(function ()
-  if #monitors > 0 then
-   neo.executeAsync("sys-init", monitors[1][2])
-  end
-  neo.executeAsync("sys-everest")
+  neo.executeAsync("sys-init", monitors[1][2])
   -- In this case the surfaces are leaked and hold references here. They have to be removed manually.
   -- Do this via a "primary event" (k.deregistration) and "deathtrap events"
   -- If a process evades the deathtrap then it clearly has reason to stay alive regardless of Everest status.
@@ -77,9 +77,6 @@ if savingThrow then
  end)
 end
 
--- Grab all available monitors when they become available
-local inSession = false
-
 local function renderingAllowed()
  -- This is a safety feature to prevent implosion due to missing monitors.
  return #monitors > 0
@@ -370,7 +367,7 @@ everestProvider(function (pkg, pid, sendSig)
   local m = 0
   if renderingAllowed() then m = 1 end
   if surfaces[1] then m = surfaces[1][1] end
-  local surf = {m, 1, 1, w, h}
+  local surf = {m, 1, 2, w, h}
   local focusState = false
   local llid = lid
   lid = lid + 1
@@ -423,8 +420,6 @@ everestProvider(function (pkg, pid, sendSig)
      handleSpan(surf, 1, 1, vtitle, bg, fg)
      return
     end
-    -- WCHAX : Wide-char-cleanup has to be done left-to-right, so this handles the important part of that.
-    handleSpan(surf, surf[4], a, " ", 0, 0)
     a = a - 1
    end
    sendSig(llid, ev, a, b, c, d, e)
@@ -476,26 +471,11 @@ end)
 -- THE EVEREST USER API ENDS (now for the session API, which just does boring stuff)
 everestSessionProvider(function (pkg, pid, sendSig)
  return {
-  startSession = function ()
-   inSession = true
-  end,
-  endSession = function (startBristol)
-   if not inSession then return end
-   local m = nil
-   if monitors[1] then
-    m = monitors[1][2]
-   end
-   inSession = false
-   for k = 1, #monitors do
-    screens.disclaim(monitors[k][2])
-    monitors[k] = nil
-   end
-   if startBristol then
-    neo.executeAsync("sys-init", m)
-   end
-   reconcileAll()
-   if not startBristol then
-    return m
+  endSession = function (gotoBristol)
+   shuttingDown = true
+   if gotoBristol then
+    -- Notably, savingThrow only triggers for error-death...
+    neo.executeAsync("sys-init", (monitors[1] or {})[2])
    end
   end
  }
@@ -562,7 +542,24 @@ local function key(ka, kc, down)
  end
 end
 
-while true do
+-- take all displays!
+local function performClaim(s3)
+ local gpu = screens.claim(s3)
+ local gpucb = gpu and (gpu())
+ if gpucb then
+  local w, h = gpucb.getResolution()
+  table.insert(monitors, {gpu, s3, w, h, -1, -1})
+  -- This is required to ensure windows are moved off of the null monitor.
+  -- Luckily, there's an obvious sign if they aren't - everest will promptly crash.
+  reconcileAll()
+ end
+end
+
+for _, v in ipairs(screens.getClaimable()) do
+ performClaim(v)
+end
+
+while not shuttingDown do
  local s = {coroutine.yield()}
  if renderingAllowed() then
   if s[1] == "h.key_down" then
@@ -634,17 +631,7 @@ while true do
  end
  if s[1] == "x.neo.sys.screens" then
   if s[2] == "available" then
-   if inSession then
-    local gpu = screens.claim(s[3])
-    local gpucb = gpu and (gpu())
-    if gpucb then
-     local w, h = gpucb.getResolution()
-     table.insert(monitors, {gpu, s[3], w, h, -1, -1})
-     -- This is required to ensure windows are moved off of the null monitor.
-     -- Luckily, there's an obvious sign if they aren't - everest will promptly crash.
-     reconcileAll()
-    end
-   end
+   performClaim(s[3])
   end
   if s[2] == "lost" then
    for k, v in ipairs(monitors) do

code/apps/sys-glacier.lua

@@ -39,7 +39,7 @@ local settings = {
  -- The list of settings is here:
  -- password
  password = "",
- ["run.sys-everest"] = "yes",
+ ["sys-init.shell"] = "sys-everest",
  ["run.sys-icecap"] = "yes",
  -- scr.w/h/d.<uuid>
 }
@@ -78,6 +78,8 @@ local monitorPool = {}
 local monitorClaims = {}
 -- [gpuAddr] = monitorAddr
 local currentGPUBinding = {}
+-- [gpuAddr] = userCount
+local currentGPUUsers = {}
 
 local function announceFreeMonitor(address, except)
  for k, v in pairs(targsRD) do
@@ -92,10 +94,18 @@ local function getGPU(monitor)
  local bestD = 0
  for v in gpus.list() do
   v.bind(monitor.address, false)
+  currentGPUBinding[v.address] = monitor.address
   local d = v.maxDepth()
   if d > bestD then
    bestG = v
    bestD = d
+   bestU = currentGPUUsers[v.address] or 0
+  elseif d == bestD then
+   if (currentGPUUsers[v.address] or 0) < bestU then
+    bestG = v
+    bestD = d
+    bestU = currentGPUUsers[v.address] or 0
+   end
   end
  end
  return bestG
@@ -124,6 +134,7 @@ local function getMonitorSettings(a)
 end
 local function setupMonitor(gpu, monitor)
  gpu.bind(monitor.address, false)
+ currentGPUBinding[gpu.address] = monitor.address
  local maxW, maxH = gpu.maxResolution()
  local maxD = gpu.maxDepth()
  local w, h, d = getMonitorSettings(monitor.address)
@@ -208,8 +219,7 @@ donkonitRDProvider(function (pkg, pid, sendSig)
  targsRD[pid] = {sendSig, function ()
   for k, v in pairs(claimed) do
    -- Nothing to really do here
-   monitorClaims[k] = nil
-   announceFreeMonitor(k, pid)
+   v(false)
   end
  end}
  return {
@@ -231,11 +241,13 @@ donkonitRDProvider(function (pkg, pid, sendSig)
       setupMonitor(gpu, v)
       gpu = gpu.address
       currentGPUBinding[gpu] = address
+      currentGPUUsers[gpu] = (currentGPUUsers[gpu] or 0) + 1
       local disclaimer = function (wasDevLoss)
        -- we lost it
        monitorClaims[address] = nil
        claimed[address] = nil
        if not wasDevLoss then
+        currentGPUUsers[gpu] = currentGPUUsers[gpu] - 1
         table.insert(monitorPool, v)
         announceFreeMonitor(address, pid)
        else
@@ -249,10 +261,7 @@ donkonitRDProvider(function (pkg, pid, sendSig)
        for v in gpus.list() do
         if v.address == gpu then
          if currentGPUBinding[gpu] ~= address then
-          local _, v2 = v.bind(address, false)
-          if v2 then
-           return
-          end
+          v.bind(address, false)
          end
          currentGPUBinding[gpu] = address
          return v
@@ -277,6 +286,7 @@ loadSettings()
 local function rescanDevs()
  monitorPool = {}
  currentGPUBinding = {}
+ currentGPUUsers = {}
  local hasGPU = gpus.list()()
  for k, v in pairs(monitorClaims) do
   v[2](true)

code/apps/sys-init.lua

@@ -58,7 +58,8 @@ local function retrieveNssMonitor(nss)
  local subpool = {}
  while not gpuG do
   if performDisclaim then
-   performDisclaim()
+   performDisclaim(true)
+   performDisclaim = nil
   end
   -- nss available - this means the monitor pool is now ready.
   -- If no monitors are available, shut down now.
@@ -98,7 +99,9 @@ local function retrieveNssMonitor(nss)
    end
   end
  
-  if not subpool[1] then error("Unable to claim any monitor.") end
+  if not subpool[1] then
+   error("None of the GPUs we got were actually usable")
+  end
   gpuG = subpool[1][1]
   screen = subpool[1][2]
  end
@@ -107,9 +110,12 @@ local function retrieveNssMonitor(nss)
  scrW, scrH = gpu.getResolution()
  rstfbDraw(gpu)
  gpu.fill(1, 1, scrW, scrH, " ")
- performDisclaim = function ()
-  for _, v in ipairs(subpool) do
-   nss.disclaim(v[2])
+ performDisclaim = function (full)
+  nss.disclaim(subpool[1][2])
+  if full then
+   for _, v in ipairs(subpool) do
+    nss.disclaim(v[2])
+   end
   end
  end
  return gpu
@@ -137,6 +143,8 @@ local function finalPrompt()
  local nss = neo.requestAccess("x.neo.sys.screens")
  if nss then
   retrieveNssMonitor(nss)
+ else
+  error("no glacier to provide GPU for the prompt")
  end
  -- This is nsm's final chance to make itself available and thus allow the password to be set
  local nsm = neo.requestAccess("x.neo.sys.manage")
@@ -266,27 +274,28 @@ local function finalPrompt()
 end
 local function postPrompt()
  local gpu = gpuG()
+ local nsm = neo.requestAccess("x.neo.sys.manage")
+ local sh = "sys-everest"
+ warnings = {"Unable to get sys-init.shell due to no NSM, using sys-everest"}
+ if nsm then
+  sh = nsm.getSetting("sys-init.shell") or sh
+  warnings = {"Starting "  .. sh}
+ end
  rstfbDraw(gpu)
- -- Begin to finish login, or fail
- local everests = neo.requestAccess("x.neo.sys.session")
- if everests then
-  local s, e = pcall(everests.startSession)
-  if not s then
-   table.insert(warnings, "Everest failed to create a session")
-   table.insert(warnings, tostring(e))
-  else
-   warnings = {"Transferring to Everest..."}
-   advDraw(gpu)
-   if performDisclaim then
-    performDisclaim()
-    -- Give Everest time (this isn't perceptible, and is really just a safety measure)
-    sleep(1)
-   end
+ advDraw(gpu)
+ performDisclaim()
+ neo.executeAsync(sh)
+ sleep(0.5)
+ for i = 1, 9 do
+  local v = neo.requestAccess("x.neo.sys.session")
+  sleep(0.5) -- Important timing - allows it to take the monitor
+  if v then
    return
   end
- else
-  table.insert(warnings, "Couldn't communicate with Everest...")
  end
+ -- ...oh. hope this works then?
+ warnings = {"That wasn't a shell. Try Safe Mode."}
+ rstfbDraw(gpu)
  advDraw(gpu)
  sleep(1)
  shutdown(true)
@@ -305,17 +314,13 @@ local function initializeSystem()
   for s in screenAc.list() do
    for g in gpuAc.list() do
     g.bind(s.address, false)
-    local w, h = g.maxResolution()
-    local whd = w * h * g.maxDepth()
+    local whd = g.maxDepth()
     if whd > scrBestWHD then
      screen = s
      gpu = g
      scrBestWHD = whd
     end
    end
-   if screen then
-    break
-   end
   end
  end
  if gpu then
@@ -413,7 +418,7 @@ end
 
 if callerPkg ~= nil then
  -- Everest can call into this to force a login screen
- -- In this case it locks Everest, then starts Bristol.
+ -- In this case Everest dies, then starts Bristol.
  -- 
  if callerPkg ~= "sys-everest" then
   return