Revert "Reland "libutils: Introduce StaticString16"""

This reverts commit c55ac92bd6b6f14778758893730415f5328da530.

Reason for revert: Breaks down-stream branches. See b/140315617

Change-Id: I4937fdf4bdcc7a44d5f10700ecf2d5e96aef7d27
Merged-In: I8da93f2c9b95183e32d4a2ea895f90c449abbe4d

1 files changed, 46 insertions, 111 deletions

diff --git a/libutils/String16.cpp b/libutils/String16.cpp
index 5c3cf3261..818b17124 100644
--- a/libutils/String16.cpp
+++ b/libutils/String16.cpp
@@ -24,21 +24,21 @@
 
 namespace android {
 
-static const StaticString16 emptyString(u"");
 static inline char16_t* getEmptyString() {
-    return const_cast<char16_t*>(emptyString.string());
+    static SharedBuffer* gEmptyStringBuf = [] {
+        SharedBuffer* buf = SharedBuffer::alloc(sizeof(char16_t));
+        char16_t* str = static_cast<char16_t*>(buf->data());
+        *str = 0;
+        return buf;
+    }();
+
+    gEmptyStringBuf->acquire();
+    return static_cast<char16_t*>(gEmptyStringBuf->data());
 }
 
 // ---------------------------------------------------------------------------
 
-void* String16::alloc(size_t size)
-{
-    SharedBuffer* buf = SharedBuffer::alloc(size);
-    buf->mClientMetadata = kIsSharedBufferAllocated;
-    return buf;
-}
-
-char16_t* String16::allocFromUTF8(const char* u8str, size_t u8len)
+static char16_t* allocFromUTF8(const char* u8str, size_t u8len)
 {
     if (u8len == 0) return getEmptyString();
 
@@ -49,7 +49,7 @@ char16_t* String16::allocFromUTF8(const char* u8str, size_t u8len)
         return getEmptyString();
     }
 
-    SharedBuffer* buf = static_cast<SharedBuffer*>(alloc(sizeof(char16_t) * (u16len + 1)));
+    SharedBuffer* buf = SharedBuffer::alloc(sizeof(char16_t)*(u16len+1));
     if (buf) {
         u8cur = (const uint8_t*) u8str;
         char16_t* u16str = (char16_t*)buf->data();
@@ -66,13 +66,13 @@ char16_t* String16::allocFromUTF8(const char* u8str, size_t u8len)
     return getEmptyString();
 }
 
-char16_t* String16::allocFromUTF16(const char16_t* u16str, size_t u16len) {
+static char16_t* allocFromUTF16(const char16_t* u16str, size_t u16len) {
     if (u16len >= SIZE_MAX / sizeof(char16_t)) {
         android_errorWriteLog(0x534e4554, "73826242");
         abort();
     }
 
-    SharedBuffer* buf = static_cast<SharedBuffer*>(alloc((u16len + 1) * sizeof(char16_t)));
+    SharedBuffer* buf = SharedBuffer::alloc((u16len + 1) * sizeof(char16_t));
     ALOG_ASSERT(buf, "Unable to allocate shared buffer");
     if (buf) {
         char16_t* str = (char16_t*)buf->data();
@@ -97,8 +97,8 @@ String16::String16(StaticLinkage)
     // having run. In this case we always allocate an empty string. It's less
     // efficient than using getEmptyString(), but we assume it's uncommon.
 
-    SharedBuffer* buf = static_cast<SharedBuffer*>(alloc(sizeof(char16_t)));
-    char16_t* data = static_cast<char16_t*>(buf->data());
+    char16_t* data = static_cast<char16_t*>(
+            SharedBuffer::alloc(sizeof(char16_t))->data());
     data[0] = 0;
     mString = data;
 }
@@ -106,7 +106,7 @@ String16::String16(StaticLinkage)
 String16::String16(const String16& o)
     : mString(o.mString)
 {
-    acquire();
+    SharedBuffer::bufferFromData(mString)->acquire();
 }
 
 String16::String16(const String16& o, size_t len, size_t begin)
@@ -136,30 +136,26 @@ String16::String16(const char* o, size_t len)
 
 String16::~String16()
 {
-    release();
+    SharedBuffer::bufferFromData(mString)->release();
 }
 
 size_t String16::size() const
 {
-    if (isStaticString()) {
-        return staticStringSize();
-    } else {
-        return SharedBuffer::sizeFromData(mString) / sizeof(char16_t) - 1;
-    }
+    return SharedBuffer::sizeFromData(mString)/sizeof(char16_t)-1;
 }
 
 void String16::setTo(const String16& other)
 {
-    release();
+    SharedBuffer::bufferFromData(other.mString)->acquire();
+    SharedBuffer::bufferFromData(mString)->release();
     mString = other.mString;
-    acquire();
 }
 
 status_t String16::setTo(const String16& other, size_t len, size_t begin)
 {
     const size_t N = other.size();
     if (begin >= N) {
-        release();
+        SharedBuffer::bufferFromData(mString)->release();
         mString = getEmptyString();
         return OK;
     }
@@ -188,7 +184,8 @@ status_t String16::setTo(const char16_t* other, size_t len)
         abort();
     }
 
-    SharedBuffer* buf = static_cast<SharedBuffer*>(editResize((len + 1) * sizeof(char16_t)));
+    SharedBuffer* buf = SharedBuffer::bufferFromData(mString)
+        ->editResize((len+1)*sizeof(char16_t));
     if (buf) {
         char16_t* str = (char16_t*)buf->data();
         memmove(str, other, len*sizeof(char16_t));
@@ -215,8 +212,8 @@ status_t String16::append(const String16& other)
         abort();
     }
 
-    SharedBuffer* buf =
-            static_cast<SharedBuffer*>(editResize((myLen + otherLen + 1) * sizeof(char16_t)));
+    SharedBuffer* buf = SharedBuffer::bufferFromData(mString)
+        ->editResize((myLen+otherLen+1)*sizeof(char16_t));
     if (buf) {
         char16_t* str = (char16_t*)buf->data();
         memcpy(str+myLen, other, (otherLen+1)*sizeof(char16_t));
@@ -241,8 +238,8 @@ status_t String16::append(const char16_t* chrs, size_t otherLen)
         abort();
     }
 
-    SharedBuffer* buf =
-            static_cast<SharedBuffer*>(editResize((myLen + otherLen + 1) * sizeof(char16_t)));
+    SharedBuffer* buf = SharedBuffer::bufferFromData(mString)
+        ->editResize((myLen+otherLen+1)*sizeof(char16_t));
     if (buf) {
         char16_t* str = (char16_t*)buf->data();
         memcpy(str+myLen, chrs, otherLen*sizeof(char16_t));
@@ -276,8 +273,8 @@ status_t String16::insert(size_t pos, const char16_t* chrs, size_t len)
            len, myLen, String8(chrs, len).string());
     #endif
 
-    SharedBuffer* buf =
-            static_cast<SharedBuffer*>(editResize((myLen + len + 1) * sizeof(char16_t)));
+    SharedBuffer* buf = SharedBuffer::bufferFromData(mString)
+        ->editResize((myLen+len+1)*sizeof(char16_t));
     if (buf) {
         char16_t* str = (char16_t*)buf->data();
         if (pos < myLen) {
@@ -341,87 +338,23 @@ bool String16::contains(const char16_t* chrs) const
     return strstr16(mString, chrs) != nullptr;
 }
 
-void* String16::edit() {
-    SharedBuffer* buf;
-    if (isStaticString()) {
-        buf = static_cast<SharedBuffer*>(alloc((size() + 1) * sizeof(char16_t)));
-        if (buf) {
-            buf->acquire();
-            memcpy(buf->data(), mString, (size() + 1) * sizeof(char16_t));
-        }
-    } else {
-        buf = SharedBuffer::bufferFromData(mString)->edit();
-        buf->mClientMetadata = kIsSharedBufferAllocated;
-    }
-    return buf;
-}
-
-void* String16::editResize(size_t newSize) {
-    SharedBuffer* buf;
-    if (isStaticString()) {
-        size_t copySize = (size() + 1) * sizeof(char16_t);
-        if (newSize < copySize) {
-            copySize = newSize;
-        }
-        buf = static_cast<SharedBuffer*>(alloc(newSize));
-        if (buf) {
-            buf->acquire();
-            memcpy(buf->data(), mString, copySize);
-        }
-    } else {
-        buf = SharedBuffer::bufferFromData(mString)->editResize(newSize);
-        buf->mClientMetadata = kIsSharedBufferAllocated;
-    }
-    return buf;
-}
-
-void String16::acquire()
-{
-    if (!isStaticString()) {
-        SharedBuffer::bufferFromData(mString)->acquire();
-    }
-}
-
-void String16::release()
-{
-    if (!isStaticString()) {
-        SharedBuffer::bufferFromData(mString)->release();
-    }
-}
-
-bool String16::isStaticString() const {
-    // See String16.h for notes on the memory layout of String16::StaticData and
-    // SharedBuffer.
-    static_assert(sizeof(SharedBuffer) - offsetof(SharedBuffer, mClientMetadata) == 4);
-    const uint32_t* p = reinterpret_cast<const uint32_t*>(mString);
-    return (*(p - 1) & kIsSharedBufferAllocated) == 0;
-}
-
-size_t String16::staticStringSize() const {
-    // See String16.h for notes on the memory layout of String16::StaticData and
-    // SharedBuffer.
-    static_assert(sizeof(SharedBuffer) - offsetof(SharedBuffer, mClientMetadata) == 4);
-    const uint32_t* p = reinterpret_cast<const uint32_t*>(mString);
-    return static_cast<size_t>(*(p - 1));
-}
-
 status_t String16::makeLower()
 {
     const size_t N = size();
     const char16_t* str = string();
-    char16_t* edited = nullptr;
+    char16_t* edit = nullptr;
     for (size_t i=0; i<N; i++) {
         const char16_t v = str[i];
         if (v >= 'A' && v <= 'Z') {
-            if (!edited) {
-                SharedBuffer* buf = static_cast<SharedBuffer*>(edit());
+            if (!edit) {
+                SharedBuffer* buf = SharedBuffer::bufferFromData(mString)->edit();
                 if (!buf) {
                     return NO_MEMORY;
                 }
-                edited = (char16_t*)buf->data();
-                mString = str = edited;
+                edit = (char16_t*)buf->data();
+                mString = str = edit;
             }
-            edited[i] = tolower((char)v);
+            edit[i] = tolower((char)v);
         }
     }
     return OK;
@@ -431,18 +364,18 @@ status_t String16::replaceAll(char16_t replaceThis, char16_t withThis)
 {
     const size_t N = size();
     const char16_t* str = string();
-    char16_t* edited = nullptr;
+    char16_t* edit = nullptr;
     for (size_t i=0; i<N; i++) {
         if (str[i] == replaceThis) {
-            if (!edited) {
-                SharedBuffer* buf = static_cast<SharedBuffer*>(edit());
+            if (!edit) {
+                SharedBuffer* buf = SharedBuffer::bufferFromData(mString)->edit();
                 if (!buf) {
                     return NO_MEMORY;
                 }
-                edited = (char16_t*)buf->data();
-                mString = str = edited;
+                edit = (char16_t*)buf->data();
+                mString = str = edit;
             }
-            edited[i] = withThis;
+            edit[i] = withThis;
         }
     }
     return OK;
@@ -452,7 +385,7 @@ status_t String16::remove(size_t len, size_t begin)
 {
     const size_t N = size();
     if (begin >= N) {
-        release();
+        SharedBuffer::bufferFromData(mString)->release();
         mString = getEmptyString();
         return OK;
     }
@@ -462,7 +395,8 @@ status_t String16::remove(size_t len, size_t begin)
     }
 
     if (begin > 0) {
-        SharedBuffer* buf = static_cast<SharedBuffer*>(editResize((N + 1) * sizeof(char16_t)));
+        SharedBuffer* buf = SharedBuffer::bufferFromData(mString)
+            ->editResize((N+1)*sizeof(char16_t));
         if (!buf) {
             return NO_MEMORY;
         }
@@ -470,7 +404,8 @@ status_t String16::remove(size_t len, size_t begin)
         memmove(str, str+begin, (N-begin+1)*sizeof(char16_t));
         mString = str;
     }
-    SharedBuffer* buf = static_cast<SharedBuffer*>(editResize((len + 1) * sizeof(char16_t)));
+    SharedBuffer* buf = SharedBuffer::bufferFromData(mString)
+        ->editResize((len+1)*sizeof(char16_t));
     if (buf) {
         char16_t* str = (char16_t*)buf->data();
         str[len] = 0;