Restructured .travis.yml to span more jobs

The core of littlefs's CI testing is the full test suite, `make test`, run
under a number of configurations:

- Processor architecture:
  - x86 (native)
  - Arm Thumb
  - MIPS
  - PowerPC
- Storage geometry:
  - rs=16   ps=16   cs=64   bs=512   (default)
  - rs=1    ps=1    cs=64   bs=4KiB  (NOR flash)
  - rs=512  ps=512  cs=512  bs=512   (eMMC)
  - rs=4KiB ps=4KiB cs=4KiB bs=32KiB (NAND flash)
- Other corner cases:
  - no intrinsics
  - no inline
  - byte-level read/writes
  - single block-cycles
  - odd block counts
  - odd block sizes

The number of different configurations we need to test quickly exceeds the
50 minute time limit Travis has on jobs. Fortunately, we can split these
tests out into multiple jobs. This seems to be the intended course of
action for large CI "builds" in Travis, as this gives Travis a finer
grain of control over limiting builds.

Unfortunately, this created a couple issues:

1. The Travis configuration isn't actually that flexible. It allows a
   single "matrix expansion" which can be generated from top-level lists
   of different configurations. But it doesn't let you generate a matrix
   from two seperate environment variable lists (for arch + geometry).

   Without multiple matrix expansions, we're stuck writing out each test
   permutation by hand.

   On the bright-side, this was a good chance to really learn how YAML
   anchors work. I'm torn because on one hand anchors add what feels
   like unnecessary complexity to a config language, on the other hand,
   they did help quite a bit in working around Travis's limitations.

2. Now that we have 47 jobs instead of 7, reporting a separate status
   for each job stops making sense.

   What I've opted for here is to use a special NAME variable to
   deduplicate jobs, and used a few state-less rules to hopefully have
   the reported status make sense most of the time.

   - Overwrite "pending" statuses so that the last job to start owns the
     most recent "pending" status
   - Don't overwrite "failure" statuses unless the job number matches
     our own (in the case of CI restarts)
   - Don't write "success" statuses unless the job number matches our
     own, this should delay a green check-mark until the last-to-start
     job finishes
   - Always overwrite non-failures with "failure" statuses

   This does mean a temporary "success" may appear if the last job
   terminates before earlier jobs. But this is the simpliest solution
   I can think of without storing some complex state somewhere.

   Note we can only report the size this way because it's cheap to
   calculate in every job.

.travis.yml

@@ -1,51 +1,64 @@
-# Environment variables
+# environment variables
 env:
   global:
     - CFLAGS=-Werror
     - MAKEFLAGS=-j
 
-# Common test script
-script:
+# common installation
+_: &install-common
+  # need toml, also pip3 isn't installed by default?
+  - sudo apt-get install python3-pip
+  - sudo pip3 install toml
+  # setup a ram-backed disk to speed up reentrant tests
+  - mkdir disks
+  - sudo mount -t tmpfs -o size=100m tmpfs disks
+  - export TFLAGS="$TFLAGS --disk=disks/disk"
+
+# test cases
+_: &test-example
   # make sure example can at least compile
-  - sed -n '/``` c/,/```/{/```/d; p;}' README.md > test.c &&
+  - sed -n '/``` c/,/```/{/```/d; p}' README.md > test.c &&
     make all CFLAGS+="
         -Duser_provided_block_device_read=NULL
         -Duser_provided_block_device_prog=NULL
         -Duser_provided_block_device_erase=NULL
         -Duser_provided_block_device_sync=NULL
         -include stdio.h"
-
-  # setup a ram-backed disk to speed up reentrant tests
-  - |
-    mkdir disks
-    sudo mount -t tmpfs -o size=100m tmpfs disks
-    export TFLAGS="$TFLAGS --disk=disks/disk"
-
-  # run tests
-  - make clean test TFLAGS+="-nrk"
-
+# default tests
+_: &test-default
+  # normal+reentrant tests
+  - make test TFLAGS+="-nrk"
 # common real-life geometries
+_: &test-nor
   # NOR flash: read/prog = 1 block = 4KiB
-  - make clean test TFLAGS+="-nrk -DLFS_READ_SIZE=1 -DLFS_BLOCK_SIZE=4096"
-  # SD card: read/prog = 512 block = 512
-  - make clean test TFLAGS+="-nrk -DLFS_READ_SIZE=512 -DLFS_BLOCK_SIZE=512"
+  - make test TFLAGS+="-nrk -DLFS_READ_SIZE=1 -DLFS_BLOCK_SIZE=4096"
+_: &test-emmc
+  # eMMC: read/prog = 512 block = 512
+  - make test TFLAGS+="-nrk -DLFS_READ_SIZE=512 -DLFS_BLOCK_SIZE=512"
+_: &test-nand
   # NAND flash: read/prog = 4KiB block = 32KiB
-  - make clean test TFLAGS+="-nrk -DLFS_READ_SIZE=4096 -DLFS_BLOCK_SIZE=\(32*1024\)"
-
-  # other extreme geometries for corner cases
-  - make clean test TFLAGS+="-nrk -DLFS_NO_INTRINSICS"
-  - make clean test TFLAGS+="-nrk -DLFS_INLINE_MAX=0"
-  - make clean test TFLAGS+="-nrk -DLFS_READ_SIZE=1 -DLFS_CACHE_SIZE=1"
-  - make clean test TFLAGS+="-nrk -DLFS_BLOCK_CYCLES=1"
-  - make clean test TFLAGS+="-nrk -DLFS_BLOCK_COUNT=1023 -DLFS_LOOKAHEAD_SIZE=256"
-  - make clean test TFLAGS+="-nrk -DLFS_READ_SIZE=11 -DLFS_BLOCK_SIZE=704"
+  - make test TFLAGS+="-nrk -DLFS_READ_SIZE=4096 -DLFS_BLOCK_SIZE=\(32*1024\)"
+# other extreme geometries that are useful for testing various corner cases
+_: &test-no-intrinsics
+  - make test TFLAGS+="-nrk -DLFS_NO_INTRINSICS"
+_: &test-no-inline
+  - make test TFLAGS+="-nrk -DLFS_INLINE_MAX=0"
+_: &test-byte-writes
+  - make test TFLAGS+="-nrk -DLFS_READ_SIZE=1 -DLFS_CACHE_SIZE=1"
+_: &test-block-cycles
+  - make test TFLAGS+="-nrk -DLFS_BLOCK_CYCLES=1"
+_: &test-odd-block-count
+  - make test TFLAGS+="-nrk -DLFS_BLOCK_COUNT=1023 -DLFS_LOOKAHEAD_SIZE=256"
+_: &test-odd-block-size
+  - make test TFLAGS+="-nrk -DLFS_READ_SIZE=11 -DLFS_BLOCK_SIZE=704"
 
+# report size 
+_: &report-size
   # compile and find the code size with the smallest configuration
-  - make clean size
+  - make -j1 clean size
         OBJ="$(ls lfs*.c | sed 's/\.c/\.o/' | tr '\n' ' ')"
         CFLAGS+="-DLFS_NO_ASSERT -DLFS_NO_DEBUG -DLFS_NO_WARN -DLFS_NO_ERROR"
         | tee sizes
-
   # update status if we succeeded, compare with master if possible
   - |
     if [ "$TRAVIS_TEST_RESULT" -eq 0 ]
@@ -53,7 +66,7 @@ script:
         CURR=$(tail -n1 sizes | awk '{print $1}')
         PREV=$(curl -u "$GEKY_BOT_STATUSES" https://api.github.com/repos/$TRAVIS_REPO_SLUG/status/master \
             | jq -re "select(.sha != \"$TRAVIS_COMMIT\")
-                | .statuses[] | select(.context == \"$STAGE/$NAME\").description
+                | .statuses[] | select(.context == \"${TRAVIS_BUILD_STAGE_NAME,,}/$NAME\").description
                 | capture(\"code size is (?<size>[0-9]+)\").size" \
             || echo 0)
   
@@ -64,82 +77,147 @@ script:
         fi
     fi
 
-# CI matrix
+# stage control
+stages:
+  - name: test
+  - name: deploy
+    if: branch = master AND type = push
+
+# job control
 jobs:
-  include:
   # native testing
-    - stage: test
+  - &x86
+    stage: test
     env:
-        - STAGE=test
       - NAME=littlefs-x86
+    install: *install-common
+    script: [*test-example, *report-size]
+  - {<<: *x86, script: [*test-default,          *report-size]}
+  - {<<: *x86, script: [*test-nor,              *report-size]}
+  - {<<: *x86, script: [*test-emmc,             *report-size]}
+  - {<<: *x86, script: [*test-nand,             *report-size]}
+  - {<<: *x86, script: [*test-no-intrinsics,    *report-size]}
+  - {<<: *x86, script: [*test-no-inline,        *report-size]}
+  - {<<: *x86, script: [*test-byte-writes,      *report-size]}
+  - {<<: *x86, script: [*test-block-cycles,     *report-size]}
+  - {<<: *x86, script: [*test-odd-block-count,  *report-size]}
+  - {<<: *x86, script: [*test-odd-block-size,   *report-size]}
 
   # cross-compile with ARM (thumb mode)
-    - stage: test
+  - &arm
+    stage: test
     env:
-        - STAGE=test
       - NAME=littlefs-arm
       - CC="arm-linux-gnueabi-gcc --static -mthumb"
-        - TFLAGS="-e qemu-arm"
+      - TFLAGS="$TFLAGS -e qemu-arm"
     install:
+      - *install-common
       - sudo apt-get install
             gcc-arm-linux-gnueabi
             libc6-dev-armel-cross
             qemu-user
       - arm-linux-gnueabi-gcc --version
       - qemu-arm -version
-
-    # cross-compile with PowerPC
-    - stage: test
-      env:
-        - STAGE=test
-        - NAME=littlefs-powerpc
-        - CC="powerpc-linux-gnu-gcc --static"
-        - TFLAGS="-e qemu-ppc"
-      install:
-        - sudo apt-get install
-              gcc-powerpc-linux-gnu
-              libc6-dev-powerpc-cross
-              qemu-user
-        - powerpc-linux-gnu-gcc --version
-        - qemu-ppc -version
+    script: [*test-example, *report-size]
+  - {<<: *arm, script: [*test-default,          *report-size]}
+  - {<<: *arm, script: [*test-nor,              *report-size]}
+  - {<<: *arm, script: [*test-emmc,             *report-size]}
+  - {<<: *arm, script: [*test-nand,             *report-size]}
+  - {<<: *arm, script: [*test-no-intrinsics,    *report-size]}
+  - {<<: *arm, script: [*test-no-inline,        *report-size]}
+  - {<<: *arm, script: [*test-byte-writes,      *report-size]}
+  - {<<: *arm, script: [*test-block-cycles,     *report-size]}
+  - {<<: *arm, script: [*test-odd-block-count,  *report-size]}
+  - {<<: *arm, script: [*test-odd-block-size,   *report-size]}
 
   # cross-compile with MIPS
-    - stage: test
+  - &mips
+    stage: test
     env:
-        - STAGE=test
       - NAME=littlefs-mips
       - CC="mips-linux-gnu-gcc --static"
-        - TFLAGS="-e qemu-mips"
+      - TFLAGS="$TFLAGS -e qemu-mips"
     install:
+      - *install-common
       - sudo apt-get install
             gcc-mips-linux-gnu
             libc6-dev-mips-cross
             qemu-user
       - mips-linux-gnu-gcc --version
       - qemu-mips -version
+    script: [*test-example, *report-size]
+  - {<<: *mips, script: [*test-default,          *report-size]}
+  - {<<: *mips, script: [*test-nor,              *report-size]}
+  - {<<: *mips, script: [*test-emmc,             *report-size]}
+  - {<<: *mips, script: [*test-nand,             *report-size]}
+  - {<<: *mips, script: [*test-no-intrinsics,    *report-size]}
+  - {<<: *mips, script: [*test-no-inline,        *report-size]}
+  - {<<: *mips, script: [*test-byte-writes,      *report-size]}
+  - {<<: *mips, script: [*test-block-cycles,     *report-size]}
+  - {<<: *mips, script: [*test-odd-block-count,  *report-size]}
+  - {<<: *mips, script: [*test-odd-block-size,   *report-size]}
+
+  # cross-compile with PowerPC
+  - &powerpc
+    stage: test
+    env:
+      - NAME=littlefs-powerpc
+      - CC="powerpc-linux-gnu-gcc --static"
+      - TFLAGS="$TFLAGS -e qemu-ppc"
+    install:
+      - *install-common
+      - sudo apt-get install
+            gcc-powerpc-linux-gnu
+            libc6-dev-powerpc-cross
+            qemu-user
+      - powerpc-linux-gnu-gcc --version
+      - qemu-ppc -version
+    script: [*test-example, *report-size]
+  - {<<: *powerpc, script: [*test-default,          *report-size]}
+  - {<<: *powerpc, script: [*test-nor,              *report-size]}
+  - {<<: *powerpc, script: [*test-emmc,             *report-size]}
+  - {<<: *powerpc, script: [*test-nand,             *report-size]}
+  - {<<: *powerpc, script: [*test-no-intrinsics,    *report-size]}
+  - {<<: *powerpc, script: [*test-no-inline,        *report-size]}
+  - {<<: *powerpc, script: [*test-byte-writes,      *report-size]}
+  - {<<: *powerpc, script: [*test-block-cycles,     *report-size]}
+  - {<<: *powerpc, script: [*test-odd-block-count,  *report-size]}
+  - {<<: *powerpc, script: [*test-odd-block-size,   *report-size]}
 
   # test under valgrind, checking for memory errors
-    - stage: test
+  - &valgrind
+    stage: test
     env:
-        - STAGE=test
       - NAME=littlefs-valgrind
-        - TFLAGS="--valgrind"
+      - TFLAGS="$TFLAGS --valgrind"
     install:
+      - *install-common
       - sudo apt-get install valgrind
       - valgrind --version
+    script: *test-example
+  - {<<: *valgrind, script: *test-default}
+  - {<<: *valgrind, script: *test-nor}
+  - {<<: *valgrind, script: *test-emmc}
+  - {<<: *valgrind, script: *test-nand}
+  - {<<: *valgrind, script: *test-no-intrinsics}
+  - {<<: *valgrind, script: *test-no-inline}
+  - {<<: *valgrind, script: *test-byte-writes}
+  - {<<: *valgrind, script: *test-block-cycles}
+  - {<<: *valgrind, script: *test-odd-block-count}
+  - {<<: *valgrind, script: *test-odd-block-size}
 
   # self-host with littlefs-fuse for fuzz test
   - stage: test
     env:
-        - STAGE=test
       - NAME=littlefs-fuse
     if: branch !~ -prefix$
     install:
+      - *install-common
       - sudo apt-get install libfuse-dev
       - git clone --depth 1 https://github.com/geky/littlefs-fuse -b v2
       - fusermount -V
       - gcc --version
-      before_script:
+
       # setup disk for littlefs-fuse
       - rm -rf littlefs-fuse/littlefs/*
       - cp -r $(git ls-tree --name-only HEAD) littlefs-fuse/littlefs
@@ -163,19 +241,19 @@ jobs:
       - ls -flh
       - make -B test_dirs test_files QUIET=1
 
-    # self-host with littlefs-fuse for fuzz test
+  # test migration using littlefs-fuse
   - stage: test
     env:
-        - STAGE=test
       - NAME=littlefs-migration
     if: branch !~ -prefix$
     install:
+      - *install-common
       - sudo apt-get install libfuse-dev
       - git clone --depth 1 https://github.com/geky/littlefs-fuse -b v2 v2
       - git clone --depth 1 https://github.com/geky/littlefs-fuse -b v1 v1
       - fusermount -V
       - gcc --version
-      before_script:
+
       # setup disk for littlefs-fuse
       - rm -rf v2/littlefs/*
       - cp -r $(git ls-tree --name-only HEAD) v2/littlefs
@@ -215,10 +293,9 @@ jobs:
       - ls -flh
       - make -B test_dirs test_files QUIET=1
 
-    # Automatically create releases
+  # automatically create releases
   - stage: deploy
     env:
-        - STAGE=deploy
       - NAME=deploy
     script:
       - |
@@ -289,45 +366,62 @@ jobs:
             }" #"
         SCRIPT
 
-# Manage statuses
+# manage statuses
 before_install:
   - |
+    # don't clobber other (not us) failures
+    if ! curl https://api.github.com/repos/$TRAVIS_REPO_SLUG/status/${TRAVIS_PULL_REQUEST_SHA:-$TRAVIS_COMMIT} \
+        | jq -e ".statuses[] | select(
+            .context == \"${TRAVIS_BUILD_STAGE_NAME,,}/$NAME\" and
+            .state == \"failure\" and
+            (.target_url | endswith(\"$TRAVIS_JOB_NUMBER\") | not))"
+    then
         curl -u "$GEKY_BOT_STATUSES" -X POST \
             https://api.github.com/repos/$TRAVIS_REPO_SLUG/statuses/${TRAVIS_PULL_REQUEST_SHA:-$TRAVIS_COMMIT} \
             -d "{
-            \"context\": \"$STAGE/$NAME\",
+                \"context\": \"${TRAVIS_BUILD_STAGE_NAME,,}/$NAME\",
                 \"state\": \"pending\",
                 \"description\": \"${STATUS:-In progress}\",
-            \"target_url\": \"https://travis-ci.org/$TRAVIS_REPO_SLUG/jobs/$TRAVIS_JOB_ID\"
+                \"target_url\": \"$TRAVIS_JOB_WEB_URL#$TRAVIS_JOB_NUMBER\"
             }"
-  - sudo apt-get install python3-pip
-  - sudo pip3 install toml
-  
+    fi
 
 after_failure:
   - |
+    # don't clobber other (not us) failures
+    if ! curl https://api.github.com/repos/$TRAVIS_REPO_SLUG/status/${TRAVIS_PULL_REQUEST_SHA:-$TRAVIS_COMMIT} \
+        | jq -e ".statuses[] | select(
+            .context == \"${TRAVIS_BUILD_STAGE_NAME,,}/$NAME\" and
+            .state == \"failure\" and
+            (.target_url | endswith(\"$TRAVIS_JOB_NUMBER\") | not))"
+    then
         curl -u "$GEKY_BOT_STATUSES" -X POST \
             https://api.github.com/repos/$TRAVIS_REPO_SLUG/statuses/${TRAVIS_PULL_REQUEST_SHA:-$TRAVIS_COMMIT} \
             -d "{
-            \"context\": \"$STAGE/$NAME\",
+                \"context\": \"${TRAVIS_BUILD_STAGE_NAME,,}/$NAME\",
                 \"state\": \"failure\",
                 \"description\": \"${STATUS:-Failed}\",
-            \"target_url\": \"https://travis-ci.org/$TRAVIS_REPO_SLUG/jobs/$TRAVIS_JOB_ID\"
+                \"target_url\": \"$TRAVIS_JOB_WEB_URL#$TRAVIS_JOB_NUMBER\"
             }"
+    fi
 
 after_success:
   - |
+    # don't clobber other (not us) failures
+    # only update if we were last job to mark in progress,
+    # this isn't perfect but is probably good enough
+    if ! curl https://api.github.com/repos/$TRAVIS_REPO_SLUG/status/${TRAVIS_PULL_REQUEST_SHA:-$TRAVIS_COMMIT} \
+        | jq -e ".statuses[] | select(
+            .context == \"${TRAVIS_BUILD_STAGE_NAME,,}/$NAME\" and
+            (.state == \"failure\" or .state == \"pending\") and
+            (.target_url | endswith(\"$TRAVIS_JOB_NUMBER\") | not))"
+    then
         curl -u "$GEKY_BOT_STATUSES" -X POST \
             https://api.github.com/repos/$TRAVIS_REPO_SLUG/statuses/${TRAVIS_PULL_REQUEST_SHA:-$TRAVIS_COMMIT} \
             -d "{
-            \"context\": \"$STAGE/$NAME\",
+                \"context\": \"${TRAVIS_BUILD_STAGE_NAME,,}/$NAME\",
                 \"state\": \"success\",
                 \"description\": \"${STATUS:-Passed}\",
-            \"target_url\": \"https://travis-ci.org/$TRAVIS_REPO_SLUG/jobs/$TRAVIS_JOB_ID\"
+                \"target_url\": \"$TRAVIS_JOB_WEB_URL#$TRAVIS_JOB_NUMBER\"
             }"
-
-# Job control
-stages:
-    - name: test
-    - name: deploy
-      if: branch = master AND type = push
+    fi