Reference assignment is atomic. Interlocked.Exchange does not do only reference assignment. It does a read of the current value of a variable, stashes away the old value, and assigns the new value to the variable, all as an atomic operation. my colleague said that on some platforms it's not guaranteed that reference assignment is atomic.
Is accessing a variable in C# an atomic operation?
C# 4 spec 5.5 Atomicity of variable references Reads and writes of the following data types are atomic: bool, char, byte, sbyte, short, ushort, uint, int, float, and reference types.In addition, reads and writes of enum types with an underlying type in the previous list are also atomic. Reads and writes of other types, including long, ulong, double, and decimal, as well as user-defined types ...
Interlocked.Exchange Method (System.Threading)
Exchange (Object, Object) Sets an object to a specified value and returns a reference to the original object, as an atomic operation. Exchange<T> (T, T) Sets a variable of the specified type T to a specified value and returns the original value, as an atomic operation. Exchange (UInt16, UInt16) Important. This API is not CLS-compliant.
Interlocked Class (System.Threading)
Compares two instances of the specified reference type T for reference equality and, if they are equal, replaces the first one. Decrement(Int32) Decrements a specified variable and stores the result, as an atomic operation. Decrement(Int64) Decrements the specified variable and stores the result, as an atomic operation. Decrement(UInt32)
How is atomicity of reference operations enforced?
To be more precise I didn't mean all reference operations, I mean mostly assignment which is atomic in for example .NET and Java. But even assignment is not obviously atomic since on most platforms you cannot reliably change value of 64 bit word in atomic way...
Interlocked.Increment Method (System.Threading)
The following example determines how many random numbers that range from 0 to 1,000 are required to generate 1,000 random numbers with a midpoint value. To keep track of the number of midpoint values, a variable, midpointCount, is set equal to 0 and incremented each time the random number generator returns a midpoint value until it reaches 10,000.
c#
MSDN is primarily MS-centric. Atomicity is much more general term. It is hard to say what you are asking if you are mixing such general term as atomicity with specific language like C#. Fetching will usually be atomic, assuming it is a double and your processor can read a double in one clock cycle.
Atomic Operation In C#. Introduction
What are Atomic operations and what are not? In C# Specification, the stamement about atomic operation is: "Reads and writes of the following data types shall be atomic: bool, char, byte, sbyte ...
Atomicity of variable references
In section 9.6, the spec states: Reads and writes of other types, including long, ulong, double, and decimal, as well as user-defined types, need not be atomic. I assume this part of the spec still comes from the days of 32-bit machines and runtimes. long, ulong, and double are all 64-bit value types.
Assignment operators (C# reference) The assignment operator = assigns the value of its right-hand operand to a variable, a property, or an indexer element given by its left-hand operand. The result of an assignment expression is the value assigned to the left-hand operand. The type of the right-hand operand must be the same as the type of the ...
Atomic Methods Thread Safety and Race Conditions in C#
Characteristics of Atomic Methods in C#: There are two fundamental characteristics of Atomic Methods in C#. First, if one thread is executing an atomic method, then another thread cannot see an intermediate state that is the operation has either not started or has already been completed. But there is no intermediate state between the beginning ...
C#
The C# ECMA specification guarantees that the following types will be written atomically: reference types, bool, char, byte, sbyte, short, ushort, uint, int and float. Values of other types—including user-defined value types—could be written into memory in multiple atomic writes.
Atomicity of variable references #372
It is clear that the documentation is inconsistent with the atomic description of read and write reference types，. I think the first sentence emphasizes the "assignment" operation。. eg: int a = 1; Student s = new Student {}; Student s2= s; In addition, generally, the operation of reference type is not guaranteed to be atomic.
c#
5.5 Atomicity of variable references. Reads and writes of the following data types are atomic: bool, char, byte, sbyte, short, ushort, uint, int, float, and reference types. In addition, reads and writes of enum types with an underlying type in the previous list are also atomic. Reads and writes of other types, including long, ulong, double ...
Are reference assignment and reading atomic operations in C#?
Description: Explores whether the assignment of a reference (instance2 = instance1) is an atomic operation in C#. "Atomicity of reference reading in C#" Code: MyClass instance = GetInstance(); // Use 'instance' in subsequent operations Description: Investigates whether reading a reference from a method (GetInstance()) is an atomic operation in ...
Making operations atomic
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Are reference assignment and reading atomic operations?
Yes, everything is guaranteed to be properly aligned unless you deliberately go out of your way to misalign stuff, meaning that reference assignment/reading is guaranteed to be atomic. Section 12.6.6 of the CLI spec goes on to say this: Unless explicit layout control (see Partition II (Controlling Instance Layout)) is used to alter the default ...
Variables
9.1 General. Variables represent storage locations. Every variable has a type that determines what values can be stored in the variable. C# is a type-safe language, and the C# compiler guarantees that values stored in variables are always of the appropriate type. The value of a variable can be changed through assignment or through use of the ...
atomic operation of reference assignment?
Callm down, TheCPUWizard. You are right that the reference allways has know value - it either points somewhere, or points nowhere (null). But, if I want to assing value if b to a, it is not atomic.A context switch can occure between the storage from b to stack and storage from stact to a, althougt on level of the C# language, it is single atomic-like operation.
C# Is value type assignment atomic?
Copying a struct is not guaranteed to be an atomic operation. As written in the C# language specification: Atomicity of variable references. Reads and writes of the following data types are atomic: bool, char , byte, sbyte, short, ushort, uint, int, float, and reference types. In addition, reads and writes of enum types with an underlying type ...
Assignment operators
In this article. The assignment operator = assigns the value of its right-hand operand to a variable, a property, or an indexer element given by its left-hand operand. The result of an assignment expression is the value assigned to the left-hand operand. The type of the right-hand operand must be the same as the type of the left-hand operand or ...
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Reference assignment is atomic. Interlocked.Exchange does not do only reference assignment. It does a read of the current value of a variable, stashes away the old value, and assigns the new value to the variable, all as an atomic operation. my colleague said that on some platforms it's not guaranteed that reference assignment is atomic.
C# 4 spec 5.5 Atomicity of variable references Reads and writes of the following data types are atomic: bool, char, byte, sbyte, short, ushort, uint, int, float, and reference types.In addition, reads and writes of enum types with an underlying type in the previous list are also atomic. Reads and writes of other types, including long, ulong, double, and decimal, as well as user-defined types ...
Exchange (Object, Object) Sets an object to a specified value and returns a reference to the original object, as an atomic operation. Exchange<T> (T, T) Sets a variable of the specified type T to a specified value and returns the original value, as an atomic operation. Exchange (UInt16, UInt16) Important. This API is not CLS-compliant.
Compares two instances of the specified reference type T for reference equality and, if they are equal, replaces the first one. Decrement(Int32) Decrements a specified variable and stores the result, as an atomic operation. Decrement(Int64) Decrements the specified variable and stores the result, as an atomic operation. Decrement(UInt32)
To be more precise I didn't mean all reference operations, I mean mostly assignment which is atomic in for example .NET and Java. But even assignment is not obviously atomic since on most platforms you cannot reliably change value of 64 bit word in atomic way...
The following example determines how many random numbers that range from 0 to 1,000 are required to generate 1,000 random numbers with a midpoint value. To keep track of the number of midpoint values, a variable, midpointCount, is set equal to 0 and incremented each time the random number generator returns a midpoint value until it reaches 10,000.
MSDN is primarily MS-centric. Atomicity is much more general term. It is hard to say what you are asking if you are mixing such general term as atomicity with specific language like C#. Fetching will usually be atomic, assuming it is a double and your processor can read a double in one clock cycle.
What are Atomic operations and what are not? In C# Specification, the stamement about atomic operation is: "Reads and writes of the following data types shall be atomic: bool, char, byte, sbyte ...
In section 9.6, the spec states: Reads and writes of other types, including long, ulong, double, and decimal, as well as user-defined types, need not be atomic. I assume this part of the spec still comes from the days of 32-bit machines and runtimes. long, ulong, and double are all 64-bit value types.
Assignment operators (C# reference) The assignment operator = assigns the value of its right-hand operand to a variable, a property, or an indexer element given by its left-hand operand. The result of an assignment expression is the value assigned to the left-hand operand. The type of the right-hand operand must be the same as the type of the ...
Characteristics of Atomic Methods in C#: There are two fundamental characteristics of Atomic Methods in C#. First, if one thread is executing an atomic method, then another thread cannot see an intermediate state that is the operation has either not started or has already been completed. But there is no intermediate state between the beginning ...
The C# ECMA specification guarantees that the following types will be written atomically: reference types, bool, char, byte, sbyte, short, ushort, uint, int and float. Values of other types—including user-defined value types—could be written into memory in multiple atomic writes.
It is clear that the documentation is inconsistent with the atomic description of read and write reference types，. I think the first sentence emphasizes the "assignment" operation。. eg: int a = 1; Student s = new Student {}; Student s2= s; In addition, generally, the operation of reference type is not guaranteed to be atomic.
5.5 Atomicity of variable references. Reads and writes of the following data types are atomic: bool, char, byte, sbyte, short, ushort, uint, int, float, and reference types. In addition, reads and writes of enum types with an underlying type in the previous list are also atomic. Reads and writes of other types, including long, ulong, double ...
Description: Explores whether the assignment of a reference (instance2 = instance1) is an atomic operation in C#. "Atomicity of reference reading in C#" Code: MyClass instance = GetInstance(); // Use 'instance' in subsequent operations Description: Investigates whether reading a reference from a method (GetInstance()) is an atomic operation in ...
Get C# 7.1 and .NET Core 2.0 - Modern Cross-Platform Development - Third Edition now with the O'Reilly learning platform. O'Reilly members experience books, live events, courses curated by job role, and more from O'Reilly and nearly 200 top publishers.
Yes, everything is guaranteed to be properly aligned unless you deliberately go out of your way to misalign stuff, meaning that reference assignment/reading is guaranteed to be atomic. Section 12.6.6 of the CLI spec goes on to say this: Unless explicit layout control (see Partition II (Controlling Instance Layout)) is used to alter the default ...
9.1 General. Variables represent storage locations. Every variable has a type that determines what values can be stored in the variable. C# is a type-safe language, and the C# compiler guarantees that values stored in variables are always of the appropriate type. The value of a variable can be changed through assignment or through use of the ...
Callm down, TheCPUWizard. You are right that the reference allways has know value - it either points somewhere, or points nowhere (null). But, if I want to assing value if b to a, it is not atomic.A context switch can occure between the storage from b to stack and storage from stact to a, althougt on level of the C# language, it is single atomic-like operation.
Copying a struct is not guaranteed to be an atomic operation. As written in the C# language specification: Atomicity of variable references. Reads and writes of the following data types are atomic: bool, char , byte, sbyte, short, ushort, uint, int, float, and reference types. In addition, reads and writes of enum types with an underlying type ...
In this article. The assignment operator = assigns the value of its right-hand operand to a variable, a property, or an indexer element given by its left-hand operand. The result of an assignment expression is the value assigned to the left-hand operand. The type of the right-hand operand must be the same as the type of the left-hand operand or ...