Add LEVELDB_EXPORT macro to export public symbols.

gcc defaults to exporting all symbols, but other linkers do not. Adding
the LEVELDB_EXPORT macro allows a project to set LEVELDB_SHARED_LIBRARY
when building/linking with leveldb as a shared library.

This is to allow leveldb to be created as a shared library on all
platforms support by Chrome and enables a fix for
https://bugs.chromium.org/p/chromium/issues/detail?id=764810.

This also has the benefit of reducing the shared library size from
418863 to 380367 bytes (64-bit Linux).

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171037148

1 files changed, 8 insertions, 5 deletions

diff --git a/include/leveldb/db.h b/include/leveldb/db.h
index bfab10a..9a18c92 100644
--- a/include/leveldb/db.h
+++ b/include/leveldb/db.h
@@ -7,6 +7,7 @@
 
 #include <stdint.h>
 #include <stdio.h>
+#include "leveldb/export.h"
 #include "leveldb/iterator.h"
 #include "leveldb/options.h"
 
@@ -24,13 +25,13 @@ class WriteBatch;
 // Abstract handle to particular state of a DB.
 // A Snapshot is an immutable object and can therefore be safely
 // accessed from multiple threads without any external synchronization.
-class Snapshot {
+class LEVELDB_EXPORT Snapshot {
  protected:
   virtual ~Snapshot();
 };
 
 // A range of keys
-struct Range {
+struct LEVELDB_EXPORT Range {
   Slice start;          // Included in the range
   Slice limit;          // Not included in the range
 
@@ -41,7 +42,7 @@ struct Range {
 // A DB is a persistent ordered map from keys to values.
 // A DB is safe for concurrent access from multiple threads without
 // any external synchronization.
-class DB {
+class LEVELDB_EXPORT DB {
  public:
   // Open the database with the specified "name".
   // Stores a pointer to a heap-allocated database in *dbptr and returns
@@ -150,13 +151,15 @@ class DB {
 
 // Destroy the contents of the specified database.
 // Be very careful using this method.
-Status DestroyDB(const std::string& name, const Options& options);
+LEVELDB_EXPORT Status DestroyDB(const std::string& name,
+                                const Options& options);
 
 // If a DB cannot be opened, you may attempt to call this method to
 // resurrect as much of the contents of the database as possible.
 // Some data may be lost, so be careful when calling this function
 // on a database that contains important information.
-Status RepairDB(const std::string& dbname, const Options& options);
+LEVELDB_EXPORT Status RepairDB(const std::string& dbname,
+                               const Options& options);
 
 }  // namespace leveldb