new round of CI improvements/fixes

for Github CI:
- exit->quit in gdb cmdlist
- remove unnecessary backtrace gdb cmd
- remove mymake output buffering for all platforms
- remove `brew update` step
- move from to-be-deprecated emscripten container
- switch to podman instead of docker
- cancel workflow if a more recent one is running

also update Travis config in sync:
- podman has to be installed manually
- try and skip `brew update`

.github/workflows/github_ci.yml

@@ -7,6 +7,11 @@ on:
     branches: [master]
 
 jobs:
+  cancel_previous:
+    name: Cancel workflows for outdated commits
+    runs-on: ubuntu-latest
+    steps:
+    - uses: technote-space/auto-cancel-redundant-job@v1
   main_matrix:
     name: Unix
     runs-on: ${{ matrix.os }}
@@ -77,7 +82,7 @@ jobs:
     - uses: actions/checkout@v2
     - name: Build
       run: |
-        docker run --rm -v $(pwd):/src trzeci/emscripten make -f Makefile.simple emscripten
+        podman run --rm -v $(pwd):/src emscripten/emsdk make -f Makefile.simple emscripten
     - name: Do a simple test
       run: |
         ls -lAF hyper.html hyper.js hyper.wasm

.github/workflows/install_deps.sh

@@ -2,7 +2,7 @@ set -x -e o pipefail
 
 
 GH_DEPS_UBUNTU="$GH_COMPILER libsdl1.2-dev libsdl-ttf2.0-dev libsdl-gfx1.2-dev libsdl-mixer1.2-dev"
-GH_DEPS_MACOS="sdl sdl_gfx sdl_mixer sdl_ttf"
+GH_DEPS_MACOS="sdl sdl_gfx sdl_mixer sdl_ttf" # macos-latest already has both gcc and clang
 GH_DEPS_MINGW64="$GH_COMPILER:x SDL:x SDL_ttf:x SDL_gfx:x SDL_mixer:x make gdb:x"
 
 if [[ "$GH_HYP_GLEW" == "glew_1" ]]; then
@@ -26,8 +26,8 @@ fi
 if [[ "$GH_OS" == "ubuntu-latest" ]]; then
   sudo apt-get -y install $GH_DEPS_UBUNTU
 elif [[ "$GH_OS" == "macos-latest" ]]; then
-  brew update
-  # macos-latest already has both gcc and clang
+  # As of 2020-09-30, brew update sometimes times out on Github CI, so we don't do it here
+  # it's also arguably not necessary because VM images already contain recent-ish homebrew database
   brew install $GH_DEPS_MACOS
   # work around https://stackoverflow.com/questions/51034399/ for now
   (cd /usr/local/include && ln -sf SDL/SDL.h)

.github/workflows/test_simple.sh

@@ -5,8 +5,7 @@ if [[ "$GH_OS" == "windows-latest" && "$GH_BUILDSYS" == "mymake" ]]; then
 
 cat << ENDOFCMDS > .github/workflows/gdb_cmds.txt
   run --version
-  backtrace
-  exit 1
+  quit 1
 ENDOFCMDS
 
   gdb --batch -x .github/workflows/gdb_cmds.txt ./hyperrogue

.travis.yml

@@ -1,6 +1,4 @@
 language: cpp
-services:
-  - docker
 matrix:
   include:
   - os: linux                           # Linux GCC, autotools
@@ -135,7 +133,7 @@ before_install:
     sudo apt-get update -qq
     sudo apt-get install -qq libsdl1.2-dev libsdl-gfx1.2-dev libsdl-mixer1.2-dev libsdl-ttf2.0-dev
   elif [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-    brew update
+    # brew update
     brew install sdl sdl_gfx sdl_mixer sdl_ttf
     # work around https://stackoverflow.com/questions/51034399/ for now
     (cd /usr/local/include && ln -sf SDL/SDL.h)
@@ -175,6 +173,14 @@ before_install:
       exit 'Unsupported OS'
     fi
   fi
+- |-
+  # Install podman if asked for
+  if [[ "$TRAVIS_BUILD_SYSTEM" == "emscripten" && "$TRAVIS_OS_NAME" == "linux" ]]; then
+    # partially stolen from https://github.com/junaruga/podman-experiment/blob/master/.travis.yml
+    sudo add-apt-repository -y ppa:projectatomic/ppa
+    sudo apt-get update -qq
+    sudo apt-get install -qq -y podman
+  fi
 
 script:
 - |-
@@ -193,7 +199,7 @@ script:
       ./mymake
     fi
   elif [[ "$TRAVIS_BUILD_SYSTEM" == "emscripten" ]]; then
-    docker run --rm -v $(pwd):/src trzeci/emscripten make -f Makefile.simple emscripten
+    podman run --rm -v $(pwd):/src docker.io/emscripten/emsdk make -f Makefile.simple emscripten
   else
     exit 'Unsupported build system'
   fi

mymake.cpp

@@ -57,7 +57,6 @@ void set_mingw64() {
   linker = "g++ -o hyper";
   opts = "-DWINDOWS -DCAP_GLEW=1 -DCAP_PNG=1";
   libs = " savepng.o hyper.res -lopengl32 -lSDL -lSDL_gfx -lSDL_mixer -lSDL_ttf -lpthread -lz -lglew32 -lpng";
-  setvbuf(stdout, NULL, _IONBF, 0); // MinGW is quirky with output buffering
   }
 
 vector<string> modules;
@@ -84,6 +83,7 @@ bool file_exists(string fname) {
   }
 
 int main(int argc, char **argv) {
+  setvbuf(stdout, nullptr, _IONBF, 0); // this should help with responsiveness of the real-time CI logs
 #if defined(MAC)
   set_mac();
 #elif defined(WINDOWS)