BluetoothFactory/DBTEnv: Pass JVM properties to environment, access DEBUG, VERBOSE via lazy DBTEnv from C++ (

DEBUG := environment 'direct_bt_debug' or JVM property 'direct_bt.debug'
VERBOSE := environment 'direct_bt_verbose' or JVM property 'direct_bt.verbose'

This changes allows passing JVM properties as C++ environment variables,
to be accessed via DBTEnv.

JVM property names are renamed from 'foo.bar' to 'jvm_foo_bar'
and can be queried via 'DBTEnv::getProperty("foo_bar")'
as it will also attempt the 'jvm_' prefix if the plain name wasn't resolved.

The singleton DBTEnv instance can be retrieved via DBTEnv::get(),
which allows lazy initialization of DEBUG, VERBOSE from environment variables.
This is required, as the JVM loads the native libraries first,
initializes all native static variables and only then
can pass the properties to the native environment via POSIX 'setenv(..)'.

Hence users should never use static initialization from native code
in such cases, otherwise they can't benefit from the unified JVM properties.

1 files changed, 43 insertions, 6 deletions

diff --git a/src/direct_bt/DBTEnv.cpp b/src/direct_bt/DBTEnv.cpp
index 7ea33e35..b76eeff5 100644
--- a/src/direct_bt/DBTEnv.cpp
+++ b/src/direct_bt/DBTEnv.cpp
@@ -30,13 +30,50 @@
 #include <vector>
 #include <cstdio>
 
-#include "DBTEnv.hpp"
+#include "direct_bt/DBTEnv.hpp"
+#include "direct_bt/dbt_debug.hpp"
 
-extern "C" {
-    #include <inttypes.h>
-    #include <unistd.h>
+using namespace direct_bt;
+
+const uint64_t DBTEnv::startupTimeMilliseconds = direct_bt::getCurrentMilliseconds();
+
+const char * DBTEnv::getProperty(const char *name) {
+    const char * value = getenv(name);
+    if( nullptr != value ) {
+        return value;
+    } else {
+        char name2[strlen(name)+4+1];
+        strcpy(name2, "jvm_");
+        strcpy(name2+4, name);
+        return getenv(name2);
+    }
 }
 
-using namespace direct_bt;
+std::string DBTEnv::getProperty(const char *name, const std::string & default_value) {
+    const char * value = getProperty(name);
+    if( nullptr != value ) {
+        PLAIN_PRINT("DBTEnv::getProperty %s (default %s) -> %s", name, default_value.c_str(), value);
+        return value;
+    } else {
+        PLAIN_PRINT("DBTEnv::getProperty %s -> null -> %s (default)", name, default_value.c_str());
+        return default_value;
+    }
+}
+
+bool DBTEnv::getBooleanProperty(const char *name, const bool default_value) {
+    const char * value = getProperty(name);
+    if( nullptr != value ) {
+        bool res = 0==strcmp("true", value);
+        PLAIN_PRINT("DBTEnv::getBooleanProperty %s (default %d) -> %d/%s", name, default_value, res, value);
+        return res;
+    } else {
+        PLAIN_PRINT("DBTEnv::getBooleanProperty %s -> null -> %d (default)", name, default_value);
+        return default_value;
+    }
+}
 
-const uint64_t DBTEnv::startupTimeMilliseconds = getCurrentMilliseconds();
+DBTEnv::DBTEnv()
+: DEBUG( DBTEnv::getBooleanProperty("direct_bt_debug", false) ),
+  VERBOSE( DBTEnv::DEBUG || DBTEnv::getBooleanProperty("direct_bt_verbose", false) )
+{
+}