[bit] Cache the build variables so we don't have to run make to figure them out unless the environment has changed.

Test: bit GooglePermissionControllerTest:*
Change-Id: Ie79226026477df22115ed1146875b82c2255bdef

3 files changed, 131 insertions, 52 deletions

diff --git a/tools/bit/main.cpp b/tools/bit/main.cpp
index a71cea1c44f9..678af7f1c72b 100644
--- a/tools/bit/main.cpp
+++ b/tools/bit/main.cpp
@@ -623,12 +623,13 @@ run_phases(vector<Target*> targets, const Options& options)
     const string buildProduct = get_required_env("TARGET_PRODUCT", false);
     const string buildVariant = get_required_env("TARGET_BUILD_VARIANT", false);
     const string buildType = get_required_env("TARGET_BUILD_TYPE", false);
-
+    const string buildOut = get_out_dir();
     chdir_or_exit(buildTop.c_str());
 
-    const string buildDevice = get_build_var("TARGET_DEVICE", false);
-    const string buildId = get_build_var("BUILD_ID", false);
-    const string buildOut = get_out_dir();
+    BuildVars buildVars(buildOut, buildProduct, buildVariant, buildType);
+
+    const string buildDevice = buildVars.GetBuildVar("TARGET_DEVICE", false);
+    const string buildId = buildVars.GetBuildVar("BUILD_ID", false);
 
     // Get the modules for the targets
     map<string,Module> modules;
@@ -1004,13 +1005,16 @@ run_phases(vector<Target*> targets, const Options& options)
 void
 run_tab_completion(const string& word)
 {
-    const string buildTop = get_required_env("ANDROID_BUILD_TOP", true);
+    const string buildTop = get_required_env("ANDROID_BUILD_TOP", false);
     const string buildProduct = get_required_env("TARGET_PRODUCT", false);
+    const string buildVariant = get_required_env("TARGET_BUILD_VARIANT", false);
+    const string buildType = get_required_env("TARGET_BUILD_TYPE", false);
     const string buildOut = get_out_dir();
-
     chdir_or_exit(buildTop.c_str());
 
-    string buildDevice = sniff_device_name(buildOut, buildProduct);
+    BuildVars buildVars(buildOut, buildProduct, buildVariant, buildType);
+
+    string buildDevice = buildVars.GetBuildVar("TARGET_DEVICE", false);
 
     map<string,Module> modules;
     read_modules(buildOut, buildDevice, &modules, true);
diff --git a/tools/bit/make.cpp b/tools/bit/make.cpp
index 5a9ab22719cb..627091321b2e 100644
--- a/tools/bit/make.cpp
+++ b/tools/bit/make.cpp
@@ -21,6 +21,7 @@
 #include "util.h"
 
 #include <json/reader.h>
+#include <json/writer.h>
 #include <json/value.h>
 
 #include <fstream>
@@ -34,22 +35,118 @@
 
 using namespace std;
 
-map<string,string> g_buildVars;
+static bool
+map_contains(const map<string,string>& m, const string& k, const string& v) {
+    map<string,string>::const_iterator it = m.find(k);
+    if (it == m.end()) {
+        return false;
+    }
+    return it->second == v;
+}
+
+static string
+make_cache_filename(const string& outDir)
+{
+    string filename(outDir);
+    return filename + "/.bit_cache";
+}
+
+BuildVars::BuildVars(const string& outDir, const string& buildProduct,
+        const string& buildVariant, const string& buildType)
+    :m_filename(),
+     m_cache()
+{
+    m_cache["TARGET_PRODUCT"] = buildProduct;
+    m_cache["TARGET_BUILD_VARIANT"] = buildVariant;
+    m_cache["TARGET_BUILD_TYPE"] = buildType;
+
+    // If we have any problems reading the file, that's ok, just do
+    // uncached calls to make / soong.
+
+    if (outDir == "") {
+        return;
+    }
+
+
+    m_filename = make_cache_filename(outDir);
+
+    std::ifstream stream(m_filename, std::ifstream::binary);
+
+    if (stream.fail()) {
+        return;
+    }
+
+    Json::Value json;
+    Json::Reader reader;
+    if (!reader.parse(stream, json)) {
+        return;
+    }
+
+    if (!json.isObject()) {
+        return;
+    }
+
+    map<string,string> cache;
+
+    vector<string> names = json.getMemberNames();
+    const int N = names.size();
+    for (int i=0; i<N; i++) {
+        const string& name = names[i];
+        const Json::Value& value = json[name];
+        if (!value.isString()) {
+            continue;
+        }
+        cache[name] = value.asString();
+    }
+
+    // If all of the base variables match, then we can use this cache.  Otherwise, use our
+    // base one.  The next time someone reads a value, the new one, with our base varaibles
+    // will be saved.
+    if (map_contains(cache, "TARGET_PRODUCT", buildProduct)
+            && map_contains(cache, "TARGET_BUILD_VARIANT", buildVariant)
+            && map_contains(cache, "TARGET_BUILD_TYPE", buildType)) {
+        m_cache = cache;
+    }
+}
+
+BuildVars::~BuildVars()
+{
+}
+
+void
+BuildVars::save()
+{
+    if (m_filename == "") {
+        return;
+    }
+
+    Json::StyledStreamWriter writer("  ");
+
+    Json::Value json(Json::objectValue);
+
+    for (map<string,string>::const_iterator it = m_cache.begin(); it != m_cache.end(); it++) {
+        json[it->first] = it->second;
+    }
+
+    std::ofstream stream(m_filename, std::ofstream::binary);
+    writer.write(stream, json);
+}
 
 string
-get_build_var(const string& name, bool quiet)
+BuildVars::GetBuildVar(const string& name, bool quiet)
 {
     int err;
 
-    map<string,string>::iterator it = g_buildVars.find(name);
-    if (it == g_buildVars.end()) {
+    map<string,string>::iterator it = m_cache.find(name);
+    if (it == m_cache.end()) {
         Command cmd("build/soong/soong_ui.bash");
         cmd.AddArg("--dumpvar-mode");
         cmd.AddArg(name);
 
         string output = trim(get_command_output(cmd, &err, quiet));
         if (err == 0) {
-            g_buildVars[name] = output;
+            m_cache[name] = output;
+            save();
             return output;
         } else {
             return string();
@@ -59,38 +156,6 @@ get_build_var(const string& name, bool quiet)
     }
 }
 
-string
-sniff_device_name(const string& buildOut, const string& product)
-{
-    string match("ro.build.product=" + product);
-
-    string base(buildOut + "/target/product");
-    DIR* dir = opendir(base.c_str());
-    if (dir == NULL) {
-        return string();
-    }
-
-    dirent* entry;
-    while ((entry = readdir(dir)) != NULL) {
-        if (entry->d_name[0] == '.') {
-            continue;
-        }
-        if (entry->d_type == DT_DIR) {
-            string filename(base + "/" + entry->d_name + "/system/build.prop");
-            vector<string> lines;
-            split_lines(&lines, read_file(filename));
-            for (size_t i=0; i<lines.size(); i++) {
-                if (lines[i] == match) {
-                    return entry->d_name;
-                }
-            }
-        }
-    }
-
-    closedir(dir);
-    return string();
-}
-
 void
 json_error(const string& filename, const char* error, bool quiet)
 {
diff --git a/tools/bit/make.h b/tools/bit/make.h
index 1c9504d62d46..db0b69f88a0e 100644
--- a/tools/bit/make.h
+++ b/tools/bit/make.h
@@ -31,16 +31,26 @@ struct Module
     vector<string> installed;
 };
 
-string get_build_var(const string& name, bool quiet);
-
 /**
- * Poke around in the out directory and try to find a device name that matches
- * our product. This is faster than running get_build_var and good enough for
- * tab completion.
- *
- * Returns the empty string if we can't find one.
+ * Class to encapsulate getting build variables. Caches the
+ * results if possible.
  */
-string sniff_device_name(const string& buildOut, const string& product);
+class BuildVars
+{
+public:
+    BuildVars(const string& outDir, const string& buildProduct,
+            const string& buildVariant, const string& buildType);
+    ~BuildVars();
+
+    string GetBuildVar(const string& name, bool quiet);
+
+private:
+    void save();
+
+    string m_filename;
+
+    map<string,string> m_cache;
+};
 
 void read_modules(const string& buildOut, const string& buildDevice,
         map<string,Module>* modules, bool quiet);