system-clock | 易学教程

How to delay seconds in android?

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问题 I want to delay seconds and show Toast,I try to SystemClock.sleep But it only show last message("10s")... Toast.makeText(MainActivity.this,"1s", Toast.LENGTH_SHORT).show(); SystemClock.sleep(5000); Toast.makeText(MainActivity.this,"5s", Toast.LENGTH_SHORT).show(); SystemClock.sleep(5000); Toast.makeText(MainActivity.this,"10s", Toast.LENGTH_SHORT).show(); That should be displayed in sequence 1s, 5s, 10s is not it? I also made reference to this practice, but it can not be achieved... How to

What does it mean by “partial ordering” and “total ordering” in the discussion of Lamport's synchronization Algorithm?

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问题 What I understand is, partial ordering and total ordering are two sets of rules. Partial ordering has Three rules: (1) if a an b are two events in the same process and a comes before b, then a->b. (2) ... (3) ... What is total ordering then? Why are the named so? 回答1: Those names stem form the fact that in a partial order not all elements are comparable while in a total order all elements are comparable: A partial order on the elements of a set is defined by three properties that have to hold

getting chrono time in specific way

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问题 I have following C code: uint64_t combine(uint32_t const sec, uint32_t const usec){ return (uint64_t) sec << 32 | usec; }; uint64_t now3(){ struct timeval tv; gettimeofday(&tv, NULL); return combine((uint32_t) tv.tv_sec, (uint32_t) tv.tv_usec); } What this do it combine 32 bit timestamp, and 32 bit "something", probably micro/nanoseconds into single 64 bit integer. I have really hard time to rewrite it with C++11 chrono. This is what I did so far, but I think this is wrong way to do it. auto

reading the system clock value?

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问题 Is there a virtual/system clock running independently when a computer is booted? How can we read that value? 回答1: Use the RDTSC x86 instruction, it reads the clocks since the system-start. Edit: On x86-64 targets the use of inline assembly is not possible anymore, use either intrinics or a external linked object file which was generated by an assembler. Do not forget to flush the processor pipeline before using this instruction. 来源： https://stackoverflow.com/questions/3253387/reading-the

Monotonically increasing time in Node.js

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问题 This question has already been answered for Javascript here, but window.performance.now() is obviously not available in Node.js. Some applications need a steady clock, i.e., a clock that monotonically increases through time, not subject to system clock drifts. For instance, Java has System.nanoTime() and C++ has std::chrono::steady_clock. Is such clock available in Node.js? 回答1: Turns out the equivalent in Node.js is process.hrtime(). As per the documentation: [The time returned from process

HAL_RCC_OscConfig takes too long (appx 170 μS), I need it to be <50 μS when waking from STOP

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问题 Development for STM32L053R8 on NUCLEO-L053R8 board. We have a system which "wakes" from sleep every 200 μS or so, does a small amount of work then goes back to sleep (Stop mode). Ideally I'd like to wake from STOP in under 50 μS. The HAL_RCC_OscConfig() function takes around 170 μS which renders this effort pointless. From what I can see the majority of time is spent with the PLL Configuration, in particular the while loop ("Wait till PLL is ready") which follows the re-enablement of the PLL

How could SystemClock.uptimeMillis() ever wrap?

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The Android docs on uptimeMillis() says: Returns milliseconds since boot, not counting time spent in deep sleep. Note : This value may get reset occasionally (before it would otherwise wrap around). It seems quite strange that the docs are worried about it ever wrapping around. After all, the method returns a long. A quick calculation yields that it would take approximately 292,271,023 years for it to ever wrap!!! So what's up with the docs? Is it really ever possible for it to wrap? Can the value perhaps wrap before it reaches the max value for a long? Is that what the docs are actually

HAL_RCC_OscConfig takes too long (appx 170 μS), I need it to be <50 μS when waking from STOP

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Development for STM32L053R8 on NUCLEO-L053R8 board. We have a system which "wakes" from sleep every 200 μS or so, does a small amount of work then goes back to sleep (Stop mode). Ideally I'd like to wake from STOP in under 50 μS. The HAL_RCC_OscConfig() function takes around 170 μS which renders this effort pointless. From what I can see the majority of time is spent with the PLL Configuration, in particular the while loop ("Wait till PLL is ready") which follows the re-enablement of the PLL (about 98 μS). /* Configure the main PLL clock source, multiplication and division factors. */ __HAL

Is there an NTP server I should be using when using Amazon's EC2 service to combat clock drift?

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问题 I’m using AWS and am on an EC2 server … [dalvarado@mymachine ~]$ uname -a Linux mydomain.org 3.14.33-26.47.amzn1.x86_64 #1 SMP Wed Feb 11 22:39:25 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux My clock is off by a minute ro so despite the fact that I already have NTPD installed and running [dalvarado@mymachine ~]$ sudo service ntpd status ntpd (pid 22963) is running... It would appear ntp packets are blocked or there is some other problem because I get this error … [dalvarado@mymachine ~]$ sudo

How to get Android system uptime and realtime from command line?

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问题 I'm writing a script containing several "adb shell" command. I also want to record the time when program execute these command in a form of realtime and uptime. I know I can get uptime and realtime through SystemClock: SystemClock.uptimeMillis(); SystemClock.elapsedRealtime(); Is there any way I can get these information from the command line? Thanks a lot! 回答1: Try: adb shell cat /proc/uptime 回答2: If you only need to-the-second accuracy, adb shell uptime will also work. Example output: up