make string's reference counting thread-safe
git-svn-id: http://skia.googlecode.com/svn/trunk@2268 2bbb7eff-a529-9590-31e7-b0007b416f81
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@ -66,7 +66,7 @@ public:
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SkString(const SkString&);
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~SkString();
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bool isEmpty() const { return fRec->fLength == 0; }
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bool isEmpty() const { return 0 == fRec->fLength; }
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size_t size() const { return (size_t) fRec->fLength; }
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const char* c_str() const { return fRec->data(); }
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char operator[](size_t n) const { return this->c_str()[n]; }
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@ -151,8 +151,8 @@ public:
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private:
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struct Rec {
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public:
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uint16_t fLength;
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uint16_t fRefCnt;
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size_t fLength;
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int32_t fRefCnt;
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char fBeginningOfData;
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char* data() { return &fBeginningOfData; }
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@ -168,7 +168,7 @@ private:
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#endif
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static const Rec gEmptyRec;
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static Rec* AllocRec(const char text[], U16CPU len);
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static Rec* AllocRec(const char text[], size_t len);
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static Rec* RefRec(Rec*);
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};
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@ -9,6 +9,7 @@
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#include "SkString.h"
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#include "SkFixed.h"
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#include "SkThread.h"
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#include "SkUtils.h"
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#include <stdarg.h>
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#include <stdio.h>
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@ -181,22 +182,20 @@ char* SkStrAppendFixed(char string[], SkFixed x) {
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///////////////////////////////////////////////////////////////////////////////
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#define kMaxRefCnt_SkString SK_MaxU16
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// the 3 values are [length] [refcnt] [terminating zero data]
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const SkString::Rec SkString::gEmptyRec = { 0, 0, 0 };
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#define SizeOfRec() (gEmptyRec.data() - (const char*)&gEmptyRec)
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SkString::Rec* SkString::AllocRec(const char text[], U16CPU len) {
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SkString::Rec* SkString::AllocRec(const char text[], size_t len) {
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Rec* rec;
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if (len == 0) {
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if (0 == len) {
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rec = const_cast<Rec*>(&gEmptyRec);
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} else {
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// add 1 for terminating 0, then align4 so we can have some slop when growing the string
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rec = (Rec*)sk_malloc_throw(SizeOfRec() + SkAlign4(len + 1));
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rec->fLength = SkToU16(len);
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rec->fLength = len;
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rec->fRefCnt = 1;
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if (text) {
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memcpy(rec->data(), text, len);
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@ -208,11 +207,7 @@ SkString::Rec* SkString::AllocRec(const char text[], U16CPU len) {
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SkString::Rec* SkString::RefRec(Rec* src) {
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if (src != &gEmptyRec) {
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if (src->fRefCnt == kMaxRefCnt_SkString) {
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src = AllocRec(src->data(), src->fLength);
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} else {
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src->fRefCnt += 1;
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}
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sk_atomic_inc(&src->fRefCnt);
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}
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return src;
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}
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@ -220,14 +215,14 @@ SkString::Rec* SkString::RefRec(Rec* src) {
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#ifdef SK_DEBUG
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void SkString::validate() const {
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// make sure know one has written over our global
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SkASSERT(gEmptyRec.fLength == 0);
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SkASSERT(gEmptyRec.fRefCnt == 0);
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SkASSERT(gEmptyRec.data()[0] == 0);
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SkASSERT(0 == gEmptyRec.fLength);
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SkASSERT(0 == gEmptyRec.fRefCnt);
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SkASSERT(0 == gEmptyRec.data()[0]);
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if (fRec != &gEmptyRec) {
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SkASSERT(fRec->fLength > 0);
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SkASSERT(fRec->fRefCnt > 0);
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SkASSERT(fRec->data()[fRec->fLength] == 0);
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SkASSERT(0 == fRec->data()[fRec->fLength]);
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}
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SkASSERT(fStr == c_str());
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}
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@ -280,7 +275,7 @@ SkString::~SkString() {
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if (fRec->fLength) {
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SkASSERT(fRec->fRefCnt > 0);
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if (--fRec->fRefCnt == 0) {
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if (sk_atomic_dec(&fRec->fRefCnt) == 1) {
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sk_free(fRec);
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}
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}
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@ -324,7 +319,7 @@ void SkString::reset() {
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if (fRec->fLength) {
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SkASSERT(fRec->fRefCnt > 0);
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if (--fRec->fRefCnt == 0) {
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if (sk_atomic_dec(&fRec->fRefCnt) == 1) {
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sk_free(fRec);
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}
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}
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@ -340,8 +335,14 @@ char* SkString::writable_str() {
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if (fRec->fLength) {
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if (fRec->fRefCnt > 1) {
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fRec->fRefCnt -= 1;
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fRec = AllocRec(fRec->data(), fRec->fLength);
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Rec* rec = AllocRec(fRec->data(), fRec->fLength);
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if (sk_atomic_dec(&fRec->fRefCnt) == 1) {
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// In this case after our check of fRecCnt > 1, we suddenly
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// did become the only owner, so now we have two copies of the
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// data (fRec and rec), so we need to delete one of them.
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sk_free(fRec);
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}
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fRec = rec;
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#ifdef SK_DEBUG
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fStr = fRec->data();
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#endif
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@ -355,9 +356,9 @@ void SkString::set(const char text[]) {
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}
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void SkString::set(const char text[], size_t len) {
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if (len == 0) {
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if (0 == len) {
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this->reset();
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} else if (fRec->fRefCnt == 1 && len <= fRec->fLength) {
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} else if (1 == fRec->fRefCnt && len <= fRec->fLength) {
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// should we resize if len <<<< fLength, to save RAM? (e.g. len < (fLength>>1))?
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// just use less of the buffer without allocating a smaller one
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char* p = this->writable_str();
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@ -365,15 +366,15 @@ void SkString::set(const char text[], size_t len) {
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memcpy(p, text, len);
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}
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p[len] = 0;
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fRec->fLength = SkToU16(len);
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} else if (fRec->fRefCnt == 1 && ((unsigned)fRec->fLength >> 2) == (len >> 2)) {
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fRec->fLength = len;
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} else if (1 == fRec->fRefCnt && (fRec->fLength >> 2) == (len >> 2)) {
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// we have spare room in the current allocation, so don't alloc a larger one
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char* p = this->writable_str();
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if (text) {
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memcpy(p, text, len);
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}
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p[len] = 0;
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fRec->fLength = SkToU16(len);
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fRec->fLength = len;
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} else {
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SkString tmp(text, len);
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this->swap(tmp);
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@ -390,7 +391,7 @@ void SkString::setUTF16(const uint16_t src[]) {
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}
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void SkString::setUTF16(const uint16_t src[], size_t count) {
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if (count == 0) {
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if (0 == count) {
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this->reset();
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} else if (count <= fRec->fLength) {
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// should we resize if len <<<< fLength, to save RAM? (e.g. len < (fLength>>1))
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@ -434,7 +435,7 @@ void SkString::insert(size_t offset, const char text[], size_t len) {
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which is equivalent for testing to (length + 1 + 3) >> 2 == (length + 1 + 3 + len) >> 2
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and we can then eliminate the +1+3 since that doesn't affec the answer
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*/
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if (fRec->fRefCnt == 1 && (length >> 2) == ((length + len) >> 2)) {
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if (1 == fRec->fRefCnt && (length >> 2) == ((length + len) >> 2)) {
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char* dst = this->writable_str();
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if (offset < length) {
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@ -443,7 +444,7 @@ void SkString::insert(size_t offset, const char text[], size_t len) {
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memcpy(dst + offset, text, len);
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dst[length + len] = 0;
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fRec->fLength = SkToU16(length + len);
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fRec->fLength = length + len;
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} else {
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/* Seems we should use realloc here, since that is safe if it fails
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(we have the original data), and might be faster than alloc/copy/free.
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