Improve compilation of tests for continuous integration:

fix #1293

* Build ASIO's non-template entities into a static library
  to reduce the compiler's memory usage during test compilation.

* Retry as single-threaded build after the first build failure.

.travis.yml

@@ -197,7 +197,7 @@ script:
   - |-
     echo "using $TOOLSET : : $COMPILER : <cxxflags>-std=$CXXSTD ;" > ~/user-config.jam
   - cd ../boost-root
-  - travis_retry libs/beast/tools/build-and-test.sh
+  - libs/beast/tools/retry.sh libs/beast/tools/build-and-test.sh
 
 after_script:
   - cat nohup.out || echo "nohup.out already deleted"

Jamfile

@@ -12,6 +12,7 @@ import feature ;
 import boost ;
 import modules ;
 import testing ;
+import ../../config/checks/config : requires ;
 
 boost.use-project ;
 
@@ -69,6 +70,20 @@ variant ubasan
 
 path-constant TEST_MAIN : include/boost/beast/_experimental/unit_test/main.cpp ;
 
+lib static_asio
+    : test/asio.cpp
+    : requirements
+        [ requires
+            cxx11_constexpr
+            cxx11_decltype
+            cxx11_hdr_tuple
+            cxx11_template_aliases
+            cxx11_variadic_templates
+        ]
+        <define>BOOST_ASIO_SEPARATE_COMPILATION
+        <link>static
+    ;
+
 project /boost/beast
   : requirements
     <implicit-dependency>/boost//headers
@@ -77,6 +92,7 @@ project /boost/beast
     <library>/boost/system//boost_system
     <library>/boost/coroutine//boost_coroutine
     <library>/boost/filesystem//boost_filesystem
+    <library>static_asio
     <threading>multi
     <runtime-link>shared
     <debug-symbols>on

test/Jamfile

@@ -22,6 +22,7 @@ project /boost/beast/test
     ]
     <include>./extern
     <define>BOOST_BEAST_ALLOW_DEPRECATED
+    <define>BOOST_ASIO_SEPARATE_COMPILATION
     ;
 
 path-constant ZLIB_SOURCES :

test/asio.cpp

@@ -0,0 +1 @@
+#include <boost/asio/impl/src.hpp>

tools/build-and-test.sh

@@ -17,7 +17,9 @@ if [[ $TRAVIS_BRANCH == "master" || $TRAVIS_BRANCH == "develop" ]]; then
     MAIN_BRANCH="1"
 fi
 
-if [[ "${TRAVIS}" == "true" ]]; then
+if [[ "${BEAST_RETRY}" == "true" ]]; then
+  JOBS=1
+elif [[ "${TRAVIS}" == "true" ]]; then
   JOBS="2"
 elif [[ $(uname -s) == "Linux" ]]; then
   # Physical cores

tools/retry.sh

@@ -0,0 +1,7 @@
+ #!/usr/bin/env bash
+
+for i in {1..3}
+do
+    $1 "${@:2:99}" && break;
+    export BEAST_RETRY="true"
+done